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About Us » Writers » Edgar B. Heylmun, PhD
Edgar B. Heylmun, PhD (Senior Writer (retired))
Articles by Edgar B. Heylmun, PhD
The Mexican Gold Belt

Mexico is a large country, much larger than the state of Alaska. It is almost as long as the US is wide. It has climates that range from tropical rainforests in the south to barren deserts in the north. The Sierra Madre is a forested plateau that reaches elevations in excess of 10,000 feet. It parallels the west coast of the country.

January 2006 (Vol. 75, No. 5)
Tucson Mountain Chaos

The Tucson Mountains are immediately west of Tucson, in southern Arizona, and include residential areas of the city. The highest peak, Wasson (Amole) Peak, reaches 4,687 feet. It is part of the great Basin-Range physiographic province, characterized by fault-block mountain ranges separated by broad desert valleys.

January 2005 (Vol. 74, No. 5)
Niobium and Tantalum

Niobium (columbium) and tantalum are related metals that usually occur together and are associated with vanadium on the periodic chart of the elements. Both metals have seen increased usage in high-tech applications in recent years because of increased availability.

January 2005 (Vol. 74, No. 5)

Carbonatites are rocks that formed from molten calcite or dolomite. The thought of calcite being molten lava is difficult to accept, but it was confirmed when it poured out of a vent in Tanzania in 1960.

February 2005 (Vol. 74, No. 6)
Resolution Copper Mine, Arizona

The Resolution copper mine is near Superior, Arizona (population 3,500), along the west side of the Pinal Mountains in central Arizona, 64 miles east of downtown Phoenix. The region receives about 16 inches of rain per year, enough to support chaparral vegetation.

March 2005 (Vol. 74, No. 7)

A pediment is a broad, gently sloping erosion surface or plain of low relief that is often found in arid and semi-arid regions at the base of a receding mountain front. The example shown is from the Palo Verde Ranch 15-minute topographic quadrangle, southwest of Tucson, Arizona. This is one of the best examples the writer has ever seen.

April 2005 (Vol. 74, No. 8)
Synclinal Oil

Most oilfields are found in anticlinal faults, or stratigraphic traps. Oil floats on water, so that it will rise to the highest point possible, above the water. If the porous or fractured sandstone or limestone that contains the oil is overlain by impervious shale, the oil can no longer rise. If the porous bed is arched upward...

April 2005 (Vol. 74, No. 8)
Lode Gold in Nicaragua

Nicaragua, a Central American country about the size of Iowa, has not been a major gold producer, yet the nation is filled with lode gold occurrences. Natural and man-made disasters have made the country one of the poorest in...

May 2005 (Vol. 74, No.9)
Goldville, Alabama

Goldville, Alabama, (pop. 61) is located in hilly and forested country at an elevation of 1,018 feet, in the Piedmont physiographic province. It is near the northern boundary of Tallapoosa County.

June 2005 (Vol. 74, No. 10)
Greenstone Belts in Minnesota

Greenstone is a dark greenish-black basaltic rock which, along with chloritized schist, forms belts up to 50 miles wide in northern Minnesota, in rocks of Late Archean age. Most belts are 2.6 to 2.9 billion years old.

August 2005 (Vol. 74, No. 12)
Gold in Vermont

The principal gold belt in Vermont extends south from the Canadian border along the east side of the Green Mountains, as far south as the Massachusetts line. The entire region was glaciated during the Great Ice Age and the glaciers contained streaks of finely-divided gold, so some of the gold found in Vermont originated in what is now Canada.

August 2005 (Vol. 74, No. 12)
Lode Gold in Honduras

Honduras, about the size of Ohio, is one of the “banana republics” in Central America. The central part of the nation is mountainous, with peaks reaching 9,000 feet.

September 2005 (Vol. 75, No. 1)
Placer Gold in Russia

Russia is the world’s largest country, some 66 million square miles that stretch over 6,000 miles, east-west, across northern Europe and Asia. The population of 150 million is only half that of the United States, being confined mostly to the European part of Russia and the southern part of Siberia.

November 2005 (Vol. 75, No. 3)
Epithermal Gold-Quartz Veins

The great mining geologist Waldemar Lindgren used the word “epithermal” to describe a type of quartz vein commonly found in desert regions of the United States and Mexico.

January 2004 (Vol. 73, No. 5)
Gold in Arkansas

Arkansas has an area of over 53,000 square miles, with a population of over 2.3 million. Natural vegetation consists of hardwood forests where not cleared for agriculture or urbanization.

January 2004 (Vol. 73, No. 5)
Old-Time Mining Geology Books

Geology books are best used by geologists, but many of the old-time books can be understood by most anyone who has an interest in rocks and minerals. Certain words or phrases may stump the layman, but just skip those parts and go on to the portions of the books that are easily understood. Some of the old-time mining geology books should be in every small miner’s collection.

February 2004 (Vol. 73, No. 6)
Gold in Australia

Australia is an island continent between the Pacific and Indian Oceans that is nearly 3 million square miles in area. Some 20 million people, mostly of British descent, live on the island, especially in coastal areas and in five major cities along the...

February 2004 (Vol. 73, No. 6)
Gold in Rotten Rock

Rotten rock (saprolite) can be found in all warm, humid regions, but is best developed in humid, subtropical climates, like that found in the American South. Outwardly, it looks like bedrock, but upon closer inspection, it can be seen that roots penetrate it and that it can be worked with a shovel or hydraulic monitor.

February 2004 (Vol. 73, No. 6)
Pocket Gold in Gneiss

Metamorphic rocks such as gneiss and schist are known for their pocket gold deposits. Such pockets may not be large enough for major mining operations, but may be very rewarding for individuals or small companies. Gold-bearing quartz veins may cut gneiss or schist, but often the veins parallel the bedding, or foliation. The origin of mineralized veins, which parallel the foliation, has been kicked around for years.

March 2004 (Vol. 73, No. 7)
Red Lake, Ontario

The mining and logging community of Red Lake, Ontario, population 5,000, is about 450 miles, as the crow flies, north of Minneapolis, Minnesota.

March 2004 (Vol. 73, No. 7)
Wall-Rock Alteration

Wall-rock (country rock) alteration is found in all hard-rock mining districts and has been caused by hydrothermal solutions in the past history of the region. The zones of alteration have a bearing on where one might drill for ore bodies. The weekend prospector does not have the tools nor knowledge to block out ore deposits, but he can narrow down his search dramatically by understanding the zones of wall-rock alteration that he sees.

April 2004 (Vol. 73, No. 8)
Gold in the Chinle Formation

The Chinle Formation, of Triassic age, underlies about 100,000 square miles in Arizona, Colorado, Nevada, New Mexico, and Utah. It adds to the scenic grandeur of the great Colorado Plateau province, noted for its high cliffs and deep canyons.

May 2004 (Vol. 73, No. 9)
Clarence King, Geologist

Clarence King was born in Rhode Island in 1842, the son of a businessman. His father died when he was 6, so he was raised by his mother. She wanted to have Clarence attend the very best schools, and even moved in order to have him in the best district. She gave him a magnifying glass on his 7th birthday, and this led to his discovery of fossil ferns in neighborhood rocks.

May 2004 (Vol. 73, No. 9)
Zeballos Gold Camp, British Columbia

The mining and logging camp of Zeballos (pop. 272) is located on an arm of Esperanza Inlet, on the southwest side of Vancouver Island, British Columbia. Vancouver Island is 301 miles, by road, and reaches elevations as high as 7,249 feet.

June 2004 (Vol. 73, No. 10)
Placer Platinum

The platinum group metals (PGMs) are divided into three that are “light,” about the same atomic weight as silver, and three that are “heavy,” about the same atomic weight as gold. The three light PGMs are ruthenium, rhodium, and palladium, and the three heavy PGMs are osmium, iridium, and platinum.

June 2004 (Vol. 73, No. 10)
Buell Park Pipe, Arizona

One of the world’s largest kimberlite pipes is located on the Navajo Indian Reservation in northern Arizona. The pipe is larger than any diamond-bearing pipe in South Africa. It is 16 miles north of Window Rock, the capital of the Navajo Nation.

July 2004 (Vol. 73, No. 11)
Flat-Fault Gold in Sonora, Mexico

Mexico is not noted for gold, but is better known for silver and copper. However, the states of Chihuahua and Sonora, in northwestern Mexico, contain some sizeable gold deposits. A number of these deposits were mined during the boom of 1982-2002. One operation that has remained active up to the present is La Herradura Mine...

July 2004 (Vol. 73, No. 11)
Gold in China

China is an enormous country, behind only Russia, the United States (incl. Alaska), and Canada in size. It has a teeming population of 1.3 billion, far ahead of any other nation. Most of the population is jammed into the eastern half of China, with the western half being only sparsely inhabited. There are 5 western provinces...

July 2004 (Vol. 73, No. 11)
Gold in Utah Laccoliths

The Colorado Plateau, much of it “Red Rock Country,” covers most of southern and eastern Utah, as well as parts of adjoining states. Elevations range from 3,600 to over 12,000 feet. Much of the region is...

August 2004 (Vol. 73, No. 12)

Greenstone is a hard, tough, altered igneous rock, usually dark green in color. The term “greenstone” has been loosely applied to all greenish rock, including peridotite, dunite, jade, serpentine, and even hydro thermally altered rocks in mining districts. True greenstone is...

August 2004 (Vol. 73, No. 12)
The Klamath Oldland

The Klamath Mountain province includes a number of separate mountain ranges, such as the Bully Choop, Marble, Salmon, Siskiyou, Trinity Alps, and Yolla Bolly, among others. They are collectively referred to as the “Klamath Mountains” in this article.

September 2004 (Vol. 74, No. 1)
Crater of Diamonds, Arkansas

Crater of Diamonds State Park is located 4 miles southeast of Murfreesboro, Arkansas...in an area of low hills, about a half-mile north of the Little Missouri River. The region receives 45 inches of rain per year, enough to support pine-oak forests. The diamond-bearing area stands out as grasslands surrounded by forests.

September 2004 (Vol. 74, No. 1)
The Guyana Highlands

The Guyana Highlands referred to here are a tropical upland area that extends from French Guiana on the east to Colombia on the west, with elevations reaching 9,219 feet. It occupies a vast and remote region between the Orinoco River on the north and the Amazon River on the south. There are mountains, tablelands, mesas, and swamps, largely impassable to those on foot.

October 2004 (Vol. 74, No. 2)

Molybdenum, referred to as “molly” by miners, is a white metal that is alloyed with iron to form hard, tough and strong steel. It was first used in World War I for armor plate on ships. Nowadays, molybdenum is routinely used to harden structural and tool steel, and to reduce corrosion.

October 2004 (Vol. 74, No. 2)
Placer PGMs in Coon Creek, California

Lower Coon Mountain is located in the Klamath Mountains, some 10 to 15 miles east of Crescent City (pop. 4,400), which rises to an elevation of 2,841 feet. It is heavily forested except for a few areas that are underlain by serpentine. The mountain, which trends northeast, is bounded on the north by Craigs Creek, and on the south by Coon Creek.

November 2004 (Vol. 74, No. 3)
The Boludo Placers, Sonora

The Boludo placers described here include gravels that have been listed under many different names, including Altar, Golden Triangle, Llanos del Oro, San Francisco, and Trincheras, among others. The placers are on desert flats at the northwest end of Sierra Santa Rosa, about 2,600 feet above sea level. It is in a region of northwest-trending mountain ranges separated by broad desert valleys.

November 2004 (Vol. 74, No. 3)
The Baja Gold Rush of 1889

Small amounts of placer gold can be found in many parts of Baja California, Mexico. The 700 mile long peninsula is mostly a desert region with many strange and unusual plants. There is also a central mountainous spine that is forested and reaches elevations as high as 10,155 feet.

December 2004 (Vol. 74, No. 4)
Beryllium in Nevada

Before the world class beryllium deposits were discovered at Spor Mountain, Utah, in 1959, Nevada was the nation’s principal producer of beryllium. Whereas beryl, found in pegmatites worldwide, is fairly common, some of the other...

January 2003 (Vol. 72, No. 5)
Border Silver

There is a sizable area that straddles the U.S.-Mexico border where native silver occurs in shear zones at relatively shallow depths. The district is in the low but rugged Pajarito Mountains, the highest point of which is 5,838 feet at Cerro Ruido, on the Mexican side. The deceptively rough terrain forced the first border surveyors, in 1855, to kill several mules and horses because of their injuries.

January 2003 (Vol. 72, No. 5)
The Steeple Rock District, New Mexico

The Steeple Rock Mining District is located in the northwest-trending Summit Mountains of southwest New Mexico, at an average elevation of 5,200 feet. The highest point in the mountains is Vanderbilt Peak, which rises to an elevation of 6,773 feet. The mountains receive about 12 inches of precipitation a year in the form of rain and occasional winter snow.

March 2003 (Vol. 72, No. 7)
Gold in Maine?

Maine forms the northeast corner of the United States, with an area of over 55,000 square miles. Its population is about 1.2 million, with the forested interior being largely unpopulated. The northeast end of the Appalachian Trail is at Mt. Katahdin, which...

March 2003 (Vol. 72, No. 7)
Gold in Gossan

Gossan is defined as being an iron-bearing capping over a sulfide deposit. It is formed by the oxidation and leaching of sulfide minerals, leaving hydrated iron oxides such as limonite and goethite, along with manganese oxides.

March 2003 (Vol. 72, No. 7)
Cripple Creek, Colorado

The historic mining town of Cripple Creek (population 600) is 43 miles, by paved highway, west of Colorado Springs, almost two miles high in the Colorado Rockies.

April 2003 (Vol. 72, No. 8)
The Ocampo District, Chihuahua

The village of Ocampo is wedged in a canyon about 178 miles, by Mexican Highway 16, west of the city of Chihuahua. It is a few miles west of Basaseachic Falls, and a few miles south of Highway 16, in high chaparral at an elevation of 6,500 feet. The completion of Highway 16 across the Sierra Madre Occidental greatly improved access to the region...

April 2003 (Vol. 72, No. 8)
Gold in Alabama

Alabama, 52,423 square miles in area, lies at the southwestern end of the Appalachian Mountains. The highest point in the state is only 2,407 feet above sea level. Summers are long and humid, whereas winters are mild.

May 2003 (Vol. 72, No. 9)
Central Coast Ranges

A series of coastal ranges, separated by narrow valleys, characterize coastal California south of Monterey. The mountains rise to 5,800 feet in elevation, with annual rainfall varying from 12 to 64 inches, depending on elevation and exposure.

May 2003 (Vol. 72, No. 9)
Platinum in Laccoliths

Laccoliths are unusual igneous features that seem to occur in the stable interior parts of continents. They are concordant igneous intrusions that have domed the overlying rocks and are circular in plan, and less than 10 miles in diameter. This article deals with some of the laccoliths found in the scenic Colorado Plateau province of Utah, Colorado, and Arizona...

May 2003 (Vol. 72, No. 9)
Dry Placers in Southern Baja

The southern tip of Baja California is dominated by the Sierra de la Laguna, a 70-mile-long mountain range that reaches elevations of 7,095 feet. The range is also known as the Sierra de la Victoria.

June 2003 (Vol. 72, No. 10)
Gold in Tennessee

The best known placer gold locality in Tennessee is the Coker Creek district, in the southeastern part of the state. The district lies within Cherokee National Forest and covers Coker Creek and its tributaries on the west side of the Smoky Mountains.

June 2003 (Vol. 72, No. 10)
Gold Deposits in Skarn

Skarn consists of coarse-grained calcium, magnesium, iron, and aluminum silicates formed by hydrothermal solutions, which replace limestone or dolomite near the contact with an igneous intrusion. The contact metamorphism is usually caused by an intrusion such as quartz monzonite, granodiorite, or similar rock type, which may or may not be mineralized.

July 2003 (Vol. 72, No. 11)
Hillside Placers

Hills and mountains that contain gold deposits will weather and erode over a long period of time, and the eroded material will move slowly downhill. Frost wedging and roots are two of several agents that can cause bedrock to be fractured and...

July 2003 (Vol. 72, No. 11)
Precious Metals in the Patagonia Mountains

The Patagonia Mountains are a small but rugged mountain range that adjoins the Mexican border some 9 to 16 miles east of the border town of Nogales. The range trends northerly for 14 miles and is about 10 miles wide, reaching an elevation...

August 2003 (Vol. 72, No. 12)
Mother Lode Gold, California

Included here is a portion of an article entitled “The Mother Lode of California” written in 1898 by Ross E. Browne. He was a son of J. Ross Browne, adventurer and writer, who won fame for his reports to the US Congress on the mineral resources of the...

August 2003 (Vol. 72, No. 12)
Klondike Gold

Rich placer gold deposits were found in the Klondike district of Yukon in 1896, and a wild gold rush ensued. The district is east and southeast of Dawson (pop. 1,300), mostly along Bonanza and Hunker Creeks, and their tributaries.

September 2003 (Vol. 73, No. 1)
Gallium and Germanium in Utah

The high-tech industries are making use of a number of so-called “minor” metals, many of which are obtained as byproducts of copper, lead, or zinc mining. Some of the minor metals have properties that are ideal for certain applications and, in some cases, advancements in technology are being held back because of a shortage of the metals.

September 2003 (Vol. 73, No. 1)
Roll-Front Uranium Deposits

If the uranium industry stages a comeback, it will not likely be a mad rush like it was in the 1950s. Except for non-radioactive uranium, most surface and near-surface deposits have been found.

October 2003 (Vol. 73, No. 2)
Hidden Features in Venezuela

Venezuela is considerably larger than the state of Texas and is located on the north coast of South America. The capital city of Caracas (pop. 4 million) is some 2,135 miles south of New York City. Most of the population is in the northern half of the nation, with paved highways connecting the principal cities and towns. The Orinoco River flows through the southern and central parts of the country, and much of the travel into the interior is along that river and its tributaries.

October 2003 (Vol. 73, No. 2)
Gold in the Philippines

The Philippine archipelago, with over 7,000 islands that stretch for 1,100 miles north-south, was settled by Malaysians several thousand years ago. Ferdinand Magellan landed and was killed there in 1521. Spaniards took over the islands in 1571, and founded Manila, which is located on a large natural harbor. After the Spanish-American war in 1898, the United States took over the Philippines, and found itself in a brutal 6-year war before gaining control of all of the islands.

October 2003 (Vol. 73, No. 2)
Continental Drift

As soon as reasonably accurate maps were made, 200 years ago, one could not help but note the parallelism of some coastlines with those on other continents. The coastlines of Africa and South America, in particular, are strikingly similar. The first scientist to write on the subject was an Austrian, Edward Suess, who put India, Africa, and South America into a supercontinent he named “Gondwanaland.” But, it was not until Alfred Wegener, a German, came out with his “Theory of Continental Drift” in 1912, that scientists took note.

November 2003 (Vol. 73, No. 3)
Gold Hill, Utah

The Gold Hill (Clifton) mining district is located 162 miles, by road, west of Salt Lake City. All but the last 12 miles of road is paved. The settlement of Gold Hill (pop. 10) lies at an elevation of 5,321 feet in desert mountains, the highest of which, Dutch Mountain, is 7,800 feet above sea level. Ponderosa pine grows at the highest elevations, with a zone of pinyons and junipers below that.

November 2003 (Vol. 73, No. 3)
Platinum in Nevada

Platinum group metals (PGMs) have been noted at a few localities in Nevada, especially in Clark County. Unfortunately, some of these occurrences have been associated, in the past, with fraudulent schemes. The amount of PGMs found so far has not been enough for commercially important mining operations, but the mere fact that PGMs are present is worthy of note.

November 2003 (Vol. 73, No. 3)
Texas "Hill Country" Gold

The scenic “Hill Country,” in the heart of Texas, is a recreational area for several large cities, including San Antonio and Austin. Most of the region lies at elevations between 300 and 1,800 feet, and forms an island of igneous and metamorphic...

December 2003 (Vol. 73, No. 4)
Oil Seeps in Arizona

Compared to California, Arizona has virtually no oil seeps. But, the great Permian Basin of West Texas has virtually none either. Arizona has something that neither California nor Texas have, and that is public lands that are open for leasing. The northern half of Arizona has more seeps and is thus of greater interest, but it would be foolish to disregard the southern half because giant oil and natural gas fields could underlie some of the broad desert valleys.

December 2003 (Vol. 73, No. 4)
Glacial Gold in Ohio

Ohio is an industrialized, midwestern state with a population of 11.5 million and an area of 40,953 square miles. Annual precipitation is about 40 inches, enough to give rise to hardwood forests...

January 2002 (Vol. 71, No. 5)
Placer Gold in New Mexico

New Mexico is not especially known for placer gold, although significant quantities have been recovered from certain districts. There are good opportunities for finding additional gold in favorable areas in the state.

February 2002 (Vol. 71, No. 6)
The Rand of South Africa

The republic of South Africa (pop. 45 million) lies at the southern end of the African continent, and has been responsible for much of the world’s gold and diamond production. The first Europeans to settle in the region were Dutch, but the British...

February 2002 (Vol. 71, No. 6)
Placer Gold Near Fairbanks, Alaska

The Fairbanks Mining District, the most productive gold district in Alaska, lies between the Tanana and Chatanika Rivers, 7 to 25 miles from Fairbanks (Pop. 35,000), in east-central Alaska. Most parts of the district are accessible by road, a rarity in Alaska.

February 2002 (Vol. 71, No. 6)
Gold in New Hampshire

New Hampshire, one of five New England states, has an area of 9,351 square miles, a bit larger than Kern County, California. It is a playground for people who live in the large urban areas in the East.

March 2002 (Vol. 71, No. 7)
Aerial Photos

Vertical aerial photographs, a form of remote sensing, are invaluable in the search for mineral deposits, and have been used for 60 years for that purpose.

March 2002 (Vol. 71, No. 7)
Alluvial Fans

Alluvial fans are essentially dry land “deltas” which can be found in all climates. However, they are best developed in arid and semi-arid regions, where they may be many square miles in area. They are built up by outpourings of silt, sand, and gravel caused by seasonal run-off, as well as by boulders and cobbles carried by flash floods.

April 2002 (Vol. 71, No. 8)
Mineralized Calderas in Colorado

A caldera is a large circular volcanic depression caused by collapse due to the removal of molten magma from an underlying magma chamber. The removal of magma is due to explosive venting of lava and pyroclastic material.

May 2002 (Vol. 71, No. 9)
Gold in Oregon

At least 6 million ounces of gold have been produced in Oregon since 1859. Since there are no accurate records of production prior to 1904, it is obvious that total gold production was considerably higher than that which has been recorded.

May 2002 (Vol. 71, No. 9)
Gold in Suriname

Suriname is a former Dutch colony on the north coast of South America, with an area of 63,000 square miles and a population of 450,000. Indians inhabited the region when Spaniards first sailed the coast in 1499.

June 2002 (Vol. 71, No. 10)
Beryllium in Utah

Much of the world’s supply of beryllium is mined by Brush-Wellman, Inc., at Spor Mountain, Utah. The district is in a harsh desert environment which receives only 6 inches of precipitation a year, barely enough to support scrubby desert growth.

June 2002 (Vol. 71, No. 10)
Fire Agate in Arizona

Agate, a banded form of chalcedony (cryptocrystalline quartz), has been used as a gemstone for over 7,000 years. Romans cut and polished agate, and this practice was taken to new heights in Germany in the 16th century.

June 2002 (Vol. 71, No. 10)
Piedmont Gold

The Piedmont region of the eastern United States extends for over 800 miles, from Alabama northeast to Pennsylvania. It includes the rolling country between the flat coastal plain to the east and the Blue Ridge Mountains to the west.

July 2002 (Vol. 71, No. 11)
Placer Gold in Arizona

Arizona is better-known for copper than for gold, but there are a number of dry placers in the western and southern parts of the state. A prolonged drought at the time of this writing has made the placers the driest they have been in recorded history. A good gold panner can find colors in many gulches and benches, far more than those that have been described in reports.

July 2002 (Vol. 71, No. 11)
Gold in Nevada

Over 135 million ounces of gold were produced in Nevada between 1858 and 2001, 107 million of that total being since 1965. Now, the so-called “Silver State” is the leading gold producer in the nation.

August 2002 (Vol. 71, No. 12)
The Bombarded 38' Parallel

A 1,200-mile long east-west zone, containing unusual geologic features, has been recognized in the eastern half of the United States for over 100 years. It coincides, in a general way, with the 38° parallel. There are as many opinions on the origin of the features as there are geologists. Most of the features are circular or oval in form, and some are concealed by younger rocks. They are found in 8 states, from Kansas east to Virginia.

August 2002 (Vol. 71, No. 12)

Every miner has encountered rattlesnakes in his work, and some may have been bitten. The writer has never been bitten, but has worked with people who have been. It is not a pleasant experience.

August 2002 (Vol. 71, No. 12)
Paleoplacers in the Black Hills

The Black Hills of western South Dakota are domal mountains that rise to 7,242 feet near Mt. Rushmore National Monument. Annual precipitation reaches 28 inches, enough to support winter sports and pine forests.

September 2002 (Vol. 72, No. 1)
PGMs in California

The occurrence of platinum-group metals (PGMs) is rather widespread in California in placer deposits, but they are not of commercial interest as things now stand.

September 2002 (Vol. 72, No. 1)
Cedros Island, Mexico

Cedros Island, 134 square miles in area, lies in the Pacific Ocean, 14 miles off the west coast of Baja California. It is 265 miles south of Ensenada and 340 miles south of San Diego. It is one of the few Mexican islands that is inhabited, with the fishing village of Puerto Cedros having a population of 400.

September 2002 (Vol. 72, No. 1)
Placer Gold in Idaho

Idaho is situated in the Rocky Mountains except for the southern third, which encompasses the Snake River Plain and desert mountains to the south. Elevations range up to 12,662 feet at Mt. Borah, with annual precipitation varying from 8 inches in the south to over 60 inches in the central mountains.

October 2002 (Vol. 72, No. 2)
Cobalt and Nickel in Missouri

Cobalt and nickel are tough silver-white metals, with similar physical properties, that frequently occur together in nature, along with copper sulfides. Cobalt and nickel are used as alloys, providing great strength and resistance...

October 2002 (Vol. 72, No. 2)
Gondwana Gold and Diamonds

Some 250 million years ago, the Earth had just one supercontinent, known as “Pangaea.” For whatever reason, the supercontinent began to break apart. South America and Africa remained joined, as “Gondwana,” until 65 million years ago, when they split apart. The obvious “fit” of South America with Africa was noted by geologists back in the 19th century, but it was not until Alfred Wegener came out with his “continental drift” hypothesis in 1912 that people took note.

October 2002 (Vol. 72, No. 2)
Mojave Desert Gold

The Mojave Desert is located in southeastern California, southern Nevada, western Arizona, and northern Sonora. Geologically, its western boundary is marked by the San Andreas and Garlock faults, but elsewhere, the boundaries are...

November 2002 (Vol. 72, No. 3)
Sandstone Silver in Texas

Sandstone silver deposits are found at several places near Van Horn, West Texas. The region is in the Basin Range province, which is characterized by low mountain ranges separated by broad desert valleys. Most of the region receives less than 10 inches of rain per year, barely enough to support scrubby desert vegetation. Van Horn (Pop. 3,000) is 121 miles, by highway, east of El Paso.

November 2002 (Vol. 72, No. 3)
Gold in North Dakota

North Dakota, 70,704 square miles in area, is situated on the Great Plains, in the geographic center of the North American continent. It is bounded on the north by Canada.

December 2002 (Vol. 72, No. 4)
The Ancient History of Gold

Man was aware of the presence of gold over 7,000 years ago, and it probably did not take him long to find out that gold was malleable and resistant to corrosion. He no doubt learned, at an early date, that objects could be fashioned from gold.

December 2002 (Vol. 72, No. 4)
Gold in Kansas and Oklahoma

The Great Plains region, contrary to popular opinion, is not entirely flat. There are areas of low hills and badlands, and it is in such areas where gold has been found. The areas of interest range from 700 to 3,000 feet in elevation, with annual precipitation ranging from 15 to 40 inches, in the form of summer thunderstorms and winter snow.

January 2001 (Vol. 70, No. 5)
Prospecting for Silver With a Geiger Counter

Light-colored volcanic tuff or tuffaceous sandstone often contains small amounts of uranium, enough to be detected with a sensitive radiation detector. Sometimes, the mass effect of the radiation is substantial.

January 2001 (Vol. 70, No. 5)
Gold in Chihuahua, Mexico

Chihuahua, about the size of Oregon, is Mexico’s largest state and one of its most prosperous, with a great influx of foreign capital. The capital city, Chihuahua (pop. 2 million), is 228 miles, by divided highway, south of El Paso, Texas. Topographically, the state can be divided into several provinces, from dry sandy deserts on the north and east, to the forested Sierra Madre Occidental on the west and southwest.

January 2001 (Vol. 70, No. 5)
History of Oil in California

Oil is a naturally occurring combustible fluid of organic origin that is commonly found in California and in many other parts of the world.

February 2001 (Vol. 70, No. 6)
Placer Gold in Washington

The state of Washington is not especially known for placer gold, yet significant amounts have been recovered in a few districts. These deposits are usually downstream from lode mining areas, some of which are in British Columbia.

February 2001 (Vol. 70, No. 6)
Greaterville, Arizona

One of the best-known placer gold localities in southern Arizona is at Greaterville, 45 miles, by road, southeast of downtown Tucson. The site of mile-high Greaterville is in grasslands and oak woodlands, on the east flank of the Santa Rita Mountains.

February 2001 (Vol. 70, No. 6)
Placer Diamonds in Venezuela

A large number of gem and industrial grade placer diamonds have been found in or near a number of creeks and rivers in Venezuela. The area involved is in the southeastern parts...and is inhabited by fierce Yanomamo Indians.

March 2001 (Vol. 70, No. 7)
Placer Gold in the Black Hills, South Dakota

During the Indian Wars in 1874, General George Custer and his men camped on French Creek in the southern Black Hills, near the present site of Custer, South Dakota. Two of his men found placer gold in French Creek. Word got out, and before long, a party of prospectors arrived. However, the government had signed a treaty with the Sioux Indians to stay out of the Black Hills. This led to prospectors sneaking in and working creeks all over the region at their own risk.

March 2001 (Vol. 70, No. 7)
Silver at Calico, California

Silver was discovered in the mountains as early as 1875, but the first “official” discovery was in 1881.

April 2001 (Vol. 70, No. 8)
The Golden Triangle of Sonora, Mexico

The “Golden Triangle” dry placer district in Sonora, Mexico, lies some 80 to 100 miles south of the border. It is in desert terrain at elevations between 1,900 and 2,300 feet above sea level.

May 2001 (Vol. 70, No. 9)
Discovery of the Mountain Pass REO Deposit

How does one go about discovering a rare earth oxide (REO) deposit when he is not familiar with the rare and unusual rocks and minerals that are found in such deposits? That was the case at Mountain Pass, California, yet the deposit was eventually discovered and mined.

May 2001 (Vol. 70, No. 9)
Gold in Guatemala

The Central American nation of Guatemala is better known for civil unrest, earthquakes, and volcanic eruptions than it is for gold. However, there is gold in the country, and there are undoubtedly many undiscovered deposits in the jungles and rainforests.

May 2001 (Vol. 70, No. 9)
Great Basin Gold

The Great Basin, first named by Capt. John Fremont in 1843, consists of a vast region of internal drainage, occupying most of Nevada and western Utah, and parts of California, Oregon, and Idaho.

June 2001 (Vol. 70, No. 10)
Uranium Deposits

The first reported occurrence of uranium in the United States was at Central City, Colorado, in 1871. However, prior to 1922, the ore was mined for its radium content, not uranium.

July 2001 (Vol. 70, No. 11)
Oil Seeps in Northern California

Indians used asphalt from oil seeps in California for caulking boats and other objects long before the white man arrived. Spaniards noted seeps as early as 1542, and the Portola expedition in 1769 used oil for wagon axles and as a fuel. Spaniards also used crude stills for obtaining lamp oil for use in the missions.

July 2001 (Vol. 70, No. 11)
Flat-Fault Gold

Gold and other valuable metals are often deposited in breccia and rubble formed by flat or gently-dipping faults. Such faults are commonly found in areas of crustal stretching caused by the movement of tectonic plates. Flat-faults are especially common in southeast California, southern Arizona, and northern Sonora, Mexico. However, they can be present anywhere that crustal stretching has occurred.

August 2001 (Vol. 70, No. 12)
Gold in Michigan

Gold was discovered on the upper peninsula of Michigan around 1845, about the same time that rich iron and copper deposits were being put into production. Despite the discovery of gold and silver, most interest centered about iron...

August 2001 (Vol. 70, No. 12)
The San Juan Mountains, Colorado

The rugged San Juan Mountains of Colorado rise to 14,309 feet and were a barrier to overland travel for many years. Precipitation, in the form of summer thundershowers and heavy winter snow, is enough to support coniferous forests.

September 2001 (Vol. 71, No. 1)
Gold in Virginia

The Piedmont region of Virginia contains many old gold mines and prospects, many of which are caved, overgrown, and difficult to find. Some mines have remained sporadically active up to the present time.

September 2001 (Vol. 71, No. 1)
Spanish Silver in Arizona

When Spaniards entered what is now Arizona, they encountered diggings made by Opata Indians. The Opata Indians, who now live and mine in the northeastern part of the state of Sonora, Mexico, were one of the few Indian tribes that was...

October 2001 (Vol. 71, No. 2)
Gold in Texas

There are numerous legends involving “lost” Spanish mines and treasures in central Texas, some of which have actually been found. The most famous mine, which remains lost, is the San Saba.

October 2001 (Vol. 71, No. 2)
Placer Gold in Utah

Utah is not known for gold, but a significant amount has been produced. Over 12 million ounces of lode and placer gold have been produced from Bingham Canyon alone. However, placer production, per se, has been miniscule compared to other western states, although a lot of dry placers may remain undiscovered.

November 2001 (Vol. 71, No. 3)
Gold in Panama

Panama is a long, narrow isthmus, 30,200 square miles in area, that separates Costa Rica from Colombia. It is best noted for the Panama Canal, which is now under the control of the Panamanian government, aided by the United States. The canal bisects the country and is an engineering marvel that was opened in 1914.

November 2001 (Vol. 71, No. 3)
Breccia Pipes

A breccia pipe, or chimney, is an irregular cylindrical mass of breccia that is often silicified and stands out as an iron-stained knob. They can be from a few feet to several hundred feet in diameter, and may or may not be mineralized.

December 2001 (Vol. 71, No. 4)
Placer Gemstones

Only the so-called “precious gems” will be considered in this article. They are diamond, ruby, sapphire, and emerald. A “gem” must be rare, hard, and durable, and possess a unique color or quality in order to be classified as a gem.

December 2001 (Vol. 71, No. 4)
Gold in Iceland?

Normally, one does not look at volcanic islands in a search for gold. However, rich gold deposits have been found in or near volcanoes at Lihir and Misima Islands near New Guinea, so one cannot dismiss gold opportunities on volcanic islands. All of Iceland is of volcanic origin, with acidic volcanic rocks like rhyolite and granophyre being present at a few localities.

December 2001 (Vol. 71, No. 4)
Mohave Mountain Placers, Arizona

There are literally hundreds of dry placer deposits in the Sonoran and Mohave Deserts of western Arizona. Many of these placer gold deposits are not described in any published books, bulletins, or reports, though placer gold enthusiasts know where...

January 2000 (Vol. 69, No. 5)
Placer PGMs in Alaska

The state of Alaska is huge, over twice the size of Texas, with most of the population in just a few towns. The northern third of the state is north of the Arctic Circle, and vast regions are only sparsely populated.

January 2000 (Vol. 69, No. 5)
Gold in Jasperoid

Jasperoid is a jasper-like siliceous rock, in which chalcedony or cryptocrystalline quartz has replaced limestone, dolomite, or shale. It forms the gangue of many important ore bodies. It is stained by iron and manganese oxides into shades of...

February 2000 (Vol. 69, No. 6)
Little Rocky Mountains, Montana

The Little Rocky Mountains are a group of wooded hills, 10 miles long and 8 miles wide, which form an island in the Great Plains of north-central Montana. They rise to 5,708 feet, 2,000 feet above the surrounding plains.

February 2000 (Vol. 69, No. 6)
Sunnyside, Arizona

The little-known Sunnyside district in Cochise County, Arizona, is on the southwest side of the Huachuca Mountains, which reach elevations in excess of 9,000 feet.

March 2000 (Vol. 69, No. 7)
Delamar District, Nevada

The Delamar (Ferguson) mining district is located in Lincoln County, Nevada, some 29 miles by road, southwest of Caliente. The district is on the west side of the Delamar Mountains at elevations between 5,900 and 6,600 feet.

March 2000 (Vol. 69, No. 7)
Gold in Washington

The state of Washington, the smallest, in area, of the western states, is dominated by the north-trending Cascade Range. The highest peak in the Cascades, Mt. Rainier, reaches an elevation of 14,411 feet.

April 2000 (Vol. 69, No. 8)
Serpentine in California

Serpentine, as used in this article, is both a rock and a mineral. The rock should be termed "serpentinite," but the word "serpentine" is in common usage for both the rock and mineral.

May 2000 (Vol. 69, No. 9)
Gold at Dale, California

The Dale Mining district is located in the Pinto Mountains, 18 to 25 miles east and southeast of Twentynine Palms, by way of the Twentynine Palms highway and the unpaved Gold Crown road.

May 2000 (Vol. 69, No. 9)
The Gold Belts of Georgia

There are a number of "gold belts" and portions of belts, which cut north-eastwardly across the Piedmont and Blue Ridge provinces of Georgia. The most prominent is the Dahlonega Belt, which extends from Alabama to North Carolina.

June 2000 (Vol. 69, No. 10)
Gondwana Gold Gravels

The German scientist, Alfred Wegener, came out with his theory of "continental drift" in 1912. He was considered a crackpot and it was half a century before geologists and planetary scientists began to take a second look at his theory.

June 2000 (Vol. 69, No. 10)
The History of Tombstone

The Tombstone Mining District of Arizona was not a major producer of silver in comparison with some districts in other states, but it has had a long and colorful history.

July 2000 (Vol. 69, No. 11)
The Colorado Mineral Belt

The 250 mile long Colorado Mineral Belt cuts diagonally across central and southwestern Colorado, in the heart of the Rocky Mountains...

July 2000 (Vol. 69, No. 11)
Quartzsite, Arizona

The town of Quartzsite, with a permanent population of about 2,000, was founded as a stage stop in 1866. It is situated on the broad La Posa Plain, a north-trending desert valley, at an elevation of 875 feet.

August 2000 (Vol. 69, No. 12)
Cuba Revisited

The island of Cuba, 720 miles in length, lies 95 miles south of Key West, Florida, and 180 miles south of Miami. The island separates the Atlantic Ocean from the Caribbean Sea. Most of the island consists of rolling country under 500 feet in elevation, but there are a few small mountain ranges.

August 2000 (Vol. 69, No. 12)
Jackson Hole Gold, Wyoming

Placer gold was found near South Pass, at the south end of the Wind River Mountains, in 1842, and lode gold was discovered in the same area in 1867. The principal gold rush was between 1867 and 1874.

September 2000 (Vol. 70, No. 1)
Lightning Creek, British Columbia

Lightning Creek is one of the famous placer gold streams in the Cariboo district of east-central British Columbia, Canada. It is 445 miles, by highway, north of Vancouver, some 50 miles east of the town of Quesnel (pop. 8,500).

September 2000 (Vol. 70, No. 1)
Massive Sulfide Deposits in Oregon

This article deals with massive sulfide deposits in the Klamath Mountains of southwestern Oregon, but it applies to massive sulfides found in California as well.

October 2000 (Vol. 70, No. 2)
Enrichment of Gold Veins

Most of the world's great gold mines are in secondary (supergene) enrichments in veins and stockwork, brought about by physical and chemical processes.

November 2000 (Vol. 70, No. 3)
Gold in Northern Baja California

The 760-mile-Iong Baja California peninsula, in Mexico, separates the Gulf of California (Sea of Cortez) from the Pacific Ocean. Most of the peninsula is a desert where the traveler can find some of the weirdest plants on Earth...

November 2000 (Vol. 70, No. 3)
Potaro District, Guyana

Guyana is a former British colony on the north coast of South America. The capital, Georgetown (pop. 250,000), is 2,200 miles southeast of Miami. The country is 83,000 square miles in area, depending on who does the counting.

December 2000 (Vol. 70, No. 4)
Prospecting With Color

Perhaps no one factor has caused more confusion in the search for ore than the attempt to use color as a guide to prospecting. Yet, there is a reason for every color seen in rocks, so it deserves to be noted.

December 2000 (Vol. 70, No. 4)
The Federal Land Survey System

When the thirteen original colonies were laid out in what is now part of the United States, they used the English system of metes and bounds.

March 1999 (Vol. 68, No. 7)
Gold in Moffat County, Colorado

The area of interest in this article is in eastern Moffat County, located in northwestern Colorado adjacent to the Wyoming line. It is a high, sagebrush prairie which ranges from 6,200 to 7,200 feet in elevation, north and northwest of the county seat of Craig (pop. 8,000).

March 1999 (Vol. 68, No. 7)
Dry Placers in the Kamma Mountains, Nevada

There are dry placer gold deposits in every county in Nevada, some of which are yet to be discovered.

April 1999 (Vol. 68, No. 8)
Gold at Ragged Top, Arizona

Ragged Top is a jagged mountain which rises to an elevation of 3,907 feet near the Silver Bell open-pit copper mine, some 34 airline miles northwest of downtown Tucson. It is an outlier of the Silver Bell Mountains...

April 1999 (Vol. 68, No. 8)
Gold at Mercury Mines

There are numerous old mercury (quicksilver) mines in the central Coast Ranges of California, from San Benito County on the south to Lake County on the north, a distance of 225 miles.

May 1999 (Vol. 68, No. 9)
Oil and Gas in Washington

The state of Washington may have undiscovered oil and gas resources, especially since drilling to date has been clustered in just a few areas.

May 1999 (Vol. 68, No. 9)
Gold in Mono County, California

Lode gold and silver mines and prospects can be found in many parts of Mono County, from the Sweetwater Mountains on the north to the White Mountains on the south, and at elevations ranging from 5,000 to 12,000 feet. Mining activity on the rugged east flank of the Sierra Nevada is now severely restricted, especially in resort areas and where lands adjoin Yosemite National Park.

June 1999 (Vol. 68, No. 10)
Gold at Quartzville, Oregon

The site of the old mining camp of Quartzville is 30 miles northeast of Sweet Home, Oregon, via a road which is paved for much of the distance. It is located in mountainous terrain along the west slope of the rugged Cascade Range, with elevations ranging from 1,600 to over 4,000 feet.

June 1999 (Vol. 68, No. 10)
Gold Near Boulder, Colorado

Several mining districts near Boulder, Colorado mark the northeast end of the 240-mile-Iong Colorado Mineral Belt, which cuts diagonally across the Rocky Mountains.

July 1999 (Vol. 68, No. 11)

Tantalum is a refractory metal which is non-toxic, ductile; easily fabricated, has a high melting point, is highly resistant to corrosion and is a good conductor of heat and electricity. It has the unique ability to transmit an alternating current in only one direction.

July 1999 (Vol. 68, No. 11)
California Diamonds

Most of the world's diamonds come from Africa and Australia, but several new discoveries in the United States and Canada have spurred interest.

July 1999 (Vol. 68, No. 11)
PGMs in the United States

Until just recently, platinum-group metals (PGMs), especially palladium, had been holding their own on the market. But, Russia has now resumed shipments and it has brought prices down.

August 1999 (Vol. 68, No. 12)
Guanajuato Silver, Mexico

For 250 years, the Guanajuato Mining District of Mexico produced 20% of the world's silver. The old colonial city of Guanajuato (pop.100,000) is wedged in a narrow canyon in the Sierra de Guanajuato, at an average elevation of 6,750 feet.

August 1999 (Vol. 68, No. 12)
The Klamath Mountains

Over 7 million ounces of gold have been produced in the Klamath Mountains of northwestern California, 64% of which has been from placers.

September 1999 (Vol. 69, No. 1)
Gold in the Drum Mountains

The Drum Mountains are located 23 to 30 airline miles northwest of Delta (pop. 2,000), in west-central Utah. The desert mountains rise to 7,233 feet and receive only 8 inches of precipitation a year.

September 1999 (Vol. 69, No. 1)
Picks & Pans: Prospecting for Lode Gold

Most of the world's ore deposits have been found by prospectors, not by geologists nor mining engineers. This article has been prepared with this fact in mind.

October 1999 (Vol. 69, No. 2)
Dry Lakes in Nevada

Desert dry lakes are the final resting place for many of the metals and compounds found within their drainage basins. Some, like Humboldt and Carson Sinks, have enormous drainage basins which include may highly-mineralized districts.

October 1999 (Vol. 69, No. 2)
Catastrophism vs. Uniformitarianism

Man has always wondered how the Earth was created, and how oceans, mountains, and other features were formed. However, until the last 200 years, most phenomena were explained by means of legends, superstitions, or religion. It is still that way in many parts of the world.

November 1999 (Vol. 69, No. 3)
Cerro Colorado Silver, Arizona

It was the first mine developed by Americans in the Cadsden Purchase of 1853. A number of small near-surface mines had been operated by Spaniards and Mexicans in the region prior to the arrival of Americans, going back as far as 1740.

November 1999 (Vol. 69, No. 3)
Prospecting With a Magnetometer

Swedes were the first to note variations in the Earth's magnetic field, circa 1640, and they were the first to use the dip needle. They made the first magnetometer in 1870.

December 1999 (Vol. 69, No. 4)
Gold in Sonora

The state of Sonora, slightly smaller in area than Utah, lies in-northwestern Mexico, adjoining Arizona to the south. It is characterized, on the east, by a high volcanic plateau, the Sierra Madre Occidental, which forms its boundary with Chihuahua.

December 1999 (Vol. 69, No. 4)