File:Calaverite in fluorite vein (Cripple Creek Diatreme, Early Oligocene, 32 Ma; Cripple Creek Mining District, Colorado, USA) 1 (18758318553).jpg

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Calaverite in a fluorite vein from the Oligocene of Colorado, USA. (field of view ~1.7 cm across)

Brassy gold = calaverite Pale purplish & dark grayish-purple = fluorite (CaF2 - calcium fluoride)

A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties. At its simplest, a mineral is a naturally-occurring solid chemical. Currently, there are over 4900 named and described minerals - about 200 of them are common and about 20 of them are very common. Mineral classification is based on anion chemistry. Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates.

The telluride minerals contain one or more telluride anions (Te-2). The tellurides are usually considered together with the sulfide minerals, the arsenide minerals, and the sulfarsenide minerals.

Calaverite is a rare precious metal telluride mineral, AuTe2 - gold telluride. This mineral volatilizes at relatively low temperatures. With heating, the tellurium component of calaverite readily vaporizes, leaving behind blebs of gold (see: www.flickr.com/photos/jsjgeology/14736894545).

Calaverite has a metallic luster, a yellowish-gold to silvery color, is moderately soft, and has a variety of crystal forms. It is known from only a few scattered localities on Earth and occurs with other telluride minerals such as sylvanite ((Au,Ag)2Te4 - gold silver telluride). Calaverite is an important gold ore mineral in precious metal telluride deposits such as the Golden Quadrilateral in Romania, near Kalgoorlie in western Australia, and the Cripple Creek Diatreme in Colorado, USA.

The beautiful specimen shown above is a calaverite-bearing fluorite vein from Colorado's Cripple Creek Mining District - a famous gold producing area. For more geologic info. on the Cripple Creek area, see: www.flickr.com/photos/jsjgeology/sets/72157645947296033

Geologic context & age: Cripple Creek Diatreme, Early Oligocene, 32 Ma

Locality: Cripple Creek Mining District, southern Teller County, central Colorado, USA


Photo gallery of calaverite:

www.mindat.org/gallery.php?min=852
Date
Source Calaverite in fluorite vein (Cripple Creek Diatreme, Early Oligocene, 32 Ma; Cripple Creek Mining District, Colorado, USA) 1
Author James St. John

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This image was originally posted to Flickr by jsj1771 at https://www.flickr.com/photos/47445767@N05/18758318553. It was reviewed on 15 July 2015 by FlickreviewR and was confirmed to be licensed under the terms of the cc-by-2.0.

15 July 2015

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current21:55, 15 July 2015Thumbnail for version as of 21:55, 15 July 20151,753 × 1,304 (2.09 MB)Natuur12 (talk | contribs)Transferred from Flickr via Flickr2Commons

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