U.S. DEPARTMENT OF THE INTERIORBUREAU OF LAND MANAGEMENT
Mineral poster and Specimens
 
Print Page

Hidden Treasures: Alaska Minerals Poster. All Photos on poster are coprighted 1998 by various photographers..

All Photos on poster are coprighted. © 1998 Michael Penn, Juneau: 3, 6, 9, 11, 15. © 1998 Al Grillo, Anchorage: 1, 2, 4, 5, 7, 8, 10, 12. © 1998 Soren Melchoir, Fairbanks 16. © 1998 Gary McWilliams 13. 

If you want to learn more about the mineral specimens on our Hidden Treasures poster, click the links at right.

Doug Toland offered his knowledge of minerals, as a BLM volunteer, to help select the specimens displayed on the poster. His mission was to locate samples that are both visually appealing and representative of the minerals found in Alaska.


1. Gold in quartz, Divide Creek, Seward Peninsula

2. Gold in Calcite, Chicken

3. Japan Law quartz twin, Green Monster Mountain

4. Copper Nuggets, Dan Creek, Kennicott Mine area

5. Gold Nugget, Brooks Range

6. Amethyst, quartz variety, near Tok, Alaska

7. Calcite called glendonite, pseudomorph after glauberite, Camden Bay

8. Rhodonite, near Tok

9. Epidote with Japan Law quartz twin, Green Monster Mountain

10. Orbicular diorite, Snowbird Mine, Talkeetna Mountains

11. Garnet, Wrangell, Alaska

12. Nephrite jade, Jade Creek and Jade Mountain

13. Fluorite, Kuiu Island

14. Gold Nugget (42 troy oz), Nolan Creek, Brooks Range

15. Cinnabar, Red Devil Mine near Sleetmute, Alaska

16. Rutilated quartz, near Wiseman, Brooks Range


Gold in quartz and gold in calcite (smaller specimen). Copyright 1998 Al Grillo, AnchorageGold in Quartz

The specimen at the top of the photo was found in 1995 at Divide Creek, Seward Peninsula. It is from a quartz system that formed at considerable depth and at temperatures between 200 and 300 degrees Celsius.

The specimen at the bottom of the photo was found in 1973 in the tailings below the Yuma dredge at Chicken, Alaska. It is calcite with numerous thin veins of native gold. This specimen is on display at the Alaska Museum of Natural History.

 

 

Japan Law quartz twin. Copyright 1998 Al Grillo, AnchorageJapan Law quartz twin

Rare Japan Law quartz twins are highly desired by collectors. This example comes from Green Monster Mountain in southeast Alaska where the twins occur either attached to epidote crystals or as doubly terminated "floaters."

 

 

 

Copper Nuggets. Gold nugget. Copyright 1998 Al Grillo, Anchorage Copper and Gold Nuggets

Copper can be found in its native state in the McCarthy area of south central Alaska.

George Fennimore collected these copper nuggets from Dan Creek (near McCarthy) back in the 1950's. Fennimore gave the 4 oz. nugget (left on photo) to Mary King, a well known "rock hound" from Palmer in the 1960's. Fennimore and King were later married at the Anchorage Pioneer Home for the elderly.

The gold nugget (center bottom) was found sometime between 1900 and 1920, probably from the Wiseman/Fairbanks/Circle/Ruby region of interior Alaska. The large 2 ounce nugget is typical of those found in central Alaska, which is famous for its production of gold nuggets.

Amethyst. Copyright 1998 Michael Penn, Juneau

Amethyst

Amethyst, a variety of quartz, has been found sporadically for years in the granitic uplands near Tok and Northway, Alaska. Light pinkish purple crystals occur as "singles" or as parallel growth clusters attached to massive quartz and weathered feldspar in pegmatite "pockets."

The six - inch specimen in the photo was chosen to illustrate the high degree of perfection and esthetic quality of Alaskan amethyst. It was collected around 1989 by Steve Stegall, an amateur rockhound and crystal carver from Oregon, who claimed he was guided to the pegmatite pocket by an innate ability to find crystals.

 

 

 

 

Calcite called 'Glendonite.' Copyright 1998 Al Grillo, Anchorage Calcite variety called Glendonite

Specimens of glendonite like this come from concretions in river bank mud near Carter Creek in northern Alaska. This specimen is 2 inches in length and weights 1.75 oz.

Sometimes a mineral crystal buried in the earth will be replaced by another mineral, but will retain the crystalline shape of the original mineral. This is called a pseudomorph (from the Greek "false form"). This sample of glendonite is a pseudomorph after another mineral called glauberite. It was found in 1980 in a small tributary to Carter Creek, about 3 miles upstream from Camden Bay along the arctic coast.

 

 

Rhodonite. Copyright 1998 Al Grillo, Anchorage Rhodonite

Named after the Greek word for "Rose", rhodonite is rarely found in crystal form. This piece was found in 1980 southwest of Tok. The specimen weighs 1.5 pounds and is about 4 inches in length.

The cabochons (cut specimens) shown here were made specially for this project by Jim Pray. The rhodonite used to make the cabochons was found 5 to 8 miles north of Kantishna, Alaska in 1968.

Rhodonite has long be used for decorative beads and other ornaments because of its pink color. In 18th century Russia, it was used extensively for decorating the Russian court.

 

 

Epidote with Japan Law quartz twin. Copyright 1998 Michael Penn, Juneau Epidote

Epidote is one of Alaska's premier specimen minerals. Green Monster Mountain produces splendid crystal specimens that are highly desired by collectors and museums worldwide. Doubly terminated crystals up to six inches and weighing several pounds have been found, usually with clusters of smaller quartz and epidote crystals.

The geologic history of the Green Monster Mountain deposit is complex, but basically it involves an early Cretaceous intrusion of magma (mostly diorite) into lime-rich sedimentary rock (now mostly schist and marble). The resultant contact metamorphic assemblage contains the minerals garnet (grossularite and andradite), calcite, quartz, epidote, magnetite and others. Hot fluids from the intruding magma carried the "nutrients" from which these minerals formed. It also produced the chambers (vugs) in which crystals could grow and develop to an extraordinary size and perfection.

The Green Monster claims are private and are being carefully mined by the owners, Doug Toland and Tom Hanna of Juneau, Alaska. Mineral collecting by others is not permitted.

 

 

Orbicular diorite. Copyright 1998 Al Grillo, Anchorage Orbicular diorite

Orbicular structures in plutonic rocks are actually more common than most geologist realize, although no one knows how they form. This specimen comes from a pipe pocket of orbicular diorite that is associated with gabbro, granite and pegmatite. The regional rock is quartz diorite.

The specimen was collected from a "world class" location, at the Snowbird Mine, Little Susitna River drainage in the Talkeetna Mountains. It weighs 11 pounds and is 8.5 inches in length.

 

Garnet. Copyright 1998 Michael Penn, Juneau Wrangell Garnet, Almandine variety

Because of their size, beautiful raspberry color and geometric perfection, garnets from Wrangell, in southeastern Alaska, have been sought by collectors worldwide for perhaps a century or more. The Wrangell garnets are an iron-aluminum variety called almandine.

At one time the Wrangell garnet locality was owned by several women who mined the garnets for gemstones; however, imperfections within the crystals limited their desirability as gemstones. It has been said that this was the first business in Alaska wholly owned by women.

The garnet locality is unusual for another reason. Long ago it was given to the children of the town of Wrangell who continue the tradition of collecting and selling specimens. Collecting is regulated; contact Wrangell officials for additional information.

The occurrence is about six miles north of Wrangell, on Garnet Creek at the mouth of the Stikine River. Sharp, translucent, modified dodecahedral crystals up to 1.5 inches across can be found in what is now biotite schist. This host rock includes large lenses or zones that are spackled with numerous garnets, some of which are twinned and intergrown. The soft mica of the schist permitted the garnets to develop to their unusual perfection.

Nephrite jade. Copyright 1998 Al Grillo, Anchorage Nephrite Jade

Shown is a nephrite jade boulder and necklace, from the Jade Creek and Jade Mountain locality, Kobuk River region, northwestern Alaska. This famous, remote, Arctic interior jade locality has an extensive history. Artifacts made from Kobuk River nephrite are hundreds of years old and have been found at archaeological sites along the Bering and Pacific coasts of Alaska and British Columbia, and the Arctic coast of Canada.

A U.S. Navy lieutenant, George M. Stoney discovered the Kobuk River source in 1886. This earned him the distinction of being the first non-Native to find nephrite in place in North America. From 1943 to 1945, the Alaska Territorial Department of Mines investigated the deposit in an attempt to find asbestos for the war effort. In 1945, eleven tons of jade and some 200 tons of asbestos were produced from the locality. Government geologists determined that the jade and asbestos at the locality occur in a 40-mile stretch of altered ultra basic rocks consisting mainly of serpentine that extends north of, and roughly parallel to, the Kobuk River.

The quality of Alaskan nephrite is highly variable; the finest material is usually found in smooth, stream-rolled boulders such as the 10-pound example featured here. Many of the boulders are covered by a thin rind of brown material, a result of weathering, which must be removed to reveal the unaltered green nephrite beneath. 

Fluorite. Copyright 1998 Gary McWilliams Fluorite

This specimen of fluorite comes from one of the numerous veins that intrude the Cornwallis limestone on the northern end of Kuiu Island in southeast Alaska. The deposit was discovered by Gary McWilliams in 1984.

The veins are composed mainly of quartz and secondarily of fluorite. Crystals such as this are found in open cavities within the veins. The flourite may be green or purple, cubic or octahedral. This specimen has an octahedral crystal structure and is 4 x 3 x 3 inches in size.

The ancient Greeks and Romans valued fluorite for its delicate colors, translucency and ease of carving. Splendid crystals are found in many localities.

 

Gold Nugget (42 troy oz)Gold Nugget

The gold nugget shown here was recovered by Silverado Mines U.S. Inc. in 1994, on Nolan Creek, in the Brooks Range of northern Alaska. It weighs 42 troy ounces and represents the tenth or eleventh largest nugget ever mined in Alaska.

 

 

 

 

Cinnabar. Copyright 1998 Michael Penn, JuneauCinnabar

Cinnabar (ruby red and pink crystals shown here) is a mineral composed of mercury and sulfur that has been found in commercial quantities at several deposits in southwestern Alaska. This fine, fist-sized "collector's choice" specimen is from the famous Red Devil Mine near Sleetmute. The specimen consists of calcite, quartz and cinnabar (including several sharp, cinnabar twins) in a black slate breccia.

Cinnabar was in high demand by Alaskan placer gold miners during the gold rush. The miners heated the cinnabar to release its mercury. They collected the liquid metal and placed it in the bottom of their sluice boxes. Fine gold, which would otherwise be washed through the sluice box, was captured by the mercury in a process called amalgamation.

Cinnabar is photo sensitive, and exposure to light over time will darken and alter the mineral. This specimen has retained the rich, deep red color of freshly mined material even though it was collected at least 30 years ago. It is currently on exhibit at the BLM's Juneau Mineral Information Center on Mayflower Island, Douglas, Alaska.

 

 

Rutilated quartz. Copyright 1998 Soren Melchoir, FairbanksRutilated Quartz

This rutilated quartz comes from the Nolan Creek drainage, in the Brooks Range of northern Alaska. The quartz crystals occur in fissures and vugs in metamorphic host rock. The crystal featured in this photo is around one inch wide, flawless, and contains numerous rutile needles ranging in color from reddish copper to brown. Some of the vugs an Nolan Creek contain crystals up to several inches long. Others have crystal clusters with rutile needles that stand alone and are not included in the quartz.

The Nolan Creek locality was found by Alaskan Joe Strunka, probably in the 1970's. The mining claims there are currently owned by Glenn and Joe Taylor. The brothers have much of the rutilated quartz faceted into gemstones, like those shown here. However, some of the crystals are worth more uncut, as unusual and excellent mineral specimens.


 
Last updated: 09-11-2009