SYLVANITE MINERAL FACTS Nevada Turquoise gem stones
The Gem and Mineral Collector's Photo Gallery by Nevada Outback


Sylvanite Mineral Facts:

Chemical Formula: (Au,Ag)Te2; 24% gold; 13% silver
Sylvanite is a telluride of gold and silver.

Colors: Metallic Silver white. Streak is gray.

Hardness: 1.5 to 2

Density: 8 to 8.2

Cleavage: One perfect cleavage on 010

Crystallography: Monoclinic
Distinct crystals rare. Structure. Usually bladed or granular. Often in skeleton forms deposited on rock surfaces and resembling writing in appearance.

Luster:. Brilliant Metallic luster

Optics: (Refractive Index)  = 1.63

Sylvanite, gold and silver telluride

Composition, Structure and Associated Minerals:
Sylvanite is silver-white or steel-gray and has a brilliant metallic luster and a yellowish gray streak. Sylvanite is more common than calaverite. It is an isomorphous mixture of gold and silver tellurides in the ratio of about 1 to 1.  It occurs in veins with native gold, quartz, fluorite, dolomite, and various sulfides  and other tellurides. Though not widespread, it is a locally important ore of gold. In crystallization sylvanite is isomorphous with calaverite. Its crystals are usually rich in planes, about 75 having been identified. Their habit is usually tabular. The mineral also occurs in skeleton crystals and in aggregates that are platy or granular. Twinning is common. Many twinned aggregates form networks suggesting writing, hence the name "Schrifterz" often applied to the mineral by the Germans.

Identification and Diagnostics
Sylvanite is e
asily fusible with a blow pipe at (1). If a little of the powdered mineral is heated in concentrated sulphuric acid the solution assumes a deep red color (an indication of tellurium). When decomposed in nitric acid leaves a rusty-colored, spongy mass of gold, and the solution with hydrochloric acid gives white precipitate of silver chloride. When heated with sodium carbonate on charcoal it gives a globule of gold and silver. Sylvanite is determined, by the above tests, by its silver color and good cleavage. Its chemical properties are the same as those of calaverite, but the silver precipitate produced by adding HC1 to its solution in HNO3 is always large. It is best distinguished from the gold telluride by its cleavage and from Petzite ((Ag,Au)2Te) and kessite (Ag2Te) by its crystallization, and by the yellow metallic globule produced when the mineral is roasted on charcoal. It is distinguishable from krennerite by its crystallization.

Occurrence, Localities and Origins:
Localities and Origin. Sylvanite is a rare mineral, and is found with gold ores and the other tellurides in veins at Offenbanya and Nagyag in Romania, in the mines at Cripple Creek and in Boulder Co., Colorado, near Kalgoorlie, Western Australia, in small quantities near Balmoral in the Black Hills, S.D., and at Moss, near Thunder Bay, Ontario. Like calaverite it was deposited by ascending magmatic waters, or by hot vapors.  It is mined with calaverite as a gold and silver ore at Cripple Creek and in Boulder Co., Colorado. The name is derived from Transylvania (now Romania), where it was first found. Its main use is as an ore of gold.

.Return to the Mineral Collectors Information Page




Please note that the author, Chris Ralph, retains all copyrights to this entire document and it may not be reproduced, quoted or copied without permission.

Turq_nev_6b.gif (5020 bytes)


Nevada Outback Gems

Find out more by checking out All of our links below:

View our Contemporary Turquoise Jewelry - Wearable Artwork! View our Unique Gem Quality Turquoise Cabochons
Premium Jewelry, with Gemstones of all types Top Quality Loose Gemstones - Gemstones of all types
Rare Crystals and Gemstone Rough, all types Our Free Colored Gemstone Information Encyclopedia
Chris' Gold Prospecting Encyclopedia Take a virtual tour of our Nevada Turquoise mines
Miners Reference Pages         California Gold Rush Stories More Info about Turquoise, the Beautiful Gem
Metal Detecting with the MXT Metal Detector Nevada Outback Gems Homepage
Build Your Own Mining Equipment Investing in Gold and Precious Metals
Basic Placer Mining More information about us - Nevada Outback Gems
Locations to Prospect for Gold The Rockhound's Corner Nevada Outback Library and Bookstore - Learn more!
Chris's Prospecting Adventures About Nevada Turquoise More Info about Gem Cutting Tanzanite Jewelry
Nevada Outback Gems Site Map Make Your Own Jewelry Buy Safely on EBay: avoid fraud and scam artists