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CROCOITE AUSTRALIAN COLLECTOR SPECIMENT 166 CTS

存货单位
spe
尺寸(毫米)
46.000 x 43.000 x 22.000mm
重量 (cts)
165.999
Treatment
No Treatment
类型
Specimen
颜色

CROCOITE -AUSTRALIA

SPECIMEN

BRIGHT HYACINTH -RED CRYSTAL ON MATRIX

TREATMENT-NONE

RARE COLLECTOR PC, NATURAL CLEAR CRYSTAL 

WEIGHT : 166 CTS APPROX.

SIZE : 46 X 43 X  22MM APPROX

Crocoite is a mineral consisting of lead chromate, PbCrO4, and crystallizing in the monoclinic crystal system. It is sometimes used as a paint, being identical in composition with the artificial product chrome yellow. It was discovered at Berezovsky deposit near Ekaterinburg in the Urals in 1766; and named crocoise by F. S. Beudant in 1832, from the Greek κροκος, saffron, in allusion to its color, a name first altered to crocoisite and afterwards to crocoite. It is found as well-developed crystals, although these are usually poorly terminated. Crystals are of a bright hyacinth-red color, translucent, and have an adamantine to vitreous lustre. On exposure to light much of the translucency and brilliancy is lost. The streak is orange-yellow; Mohs hardness is 2.5–3; and the specific gravity is 6.0. In the Urals the crystals are found in quartz-veins traversing granite or gneiss. Other localities which have yielded good crystallized specimens are Congonhas do Campo near Ouro Preto in Brazil, Luzon in the Philippines, and Mutare in Mashonaland.

Gold is often found associated with this mineral. Exceptional examples of crocoite crystals have been found in the Adelaide Mine at Dundas, Tasmania; they are long slender prisms, 3 to 4 inches (7.5 to 10 cm) in length, with a brilliant lustre and color. Crocoite is also the official Tasmanian mineral emblem.

Associated with crocoite at Berezovsk are the similar minerals phoenicochroite and vauquelinite. The former is a basic lead chromate, Pb2CrO5, and the latter a lead and copper phosphate-chromate, Pb2CuCrO4PO4OH. Vauquelinite forms brown or green monoclinic crystals, and was named after L. N. Vauquelin, who in 1797 discovered (simultaneously with and independently of M. H. Klaproth) the element chromium in crocoite.

Relative rarity of crocoite is connected with specific conditions required for its formation: an oxidation zone of lead ore bed and presence of ultramafic rocks serving as the source of chromium (in chromite). Oxidation of Cr3+ into CrO42- (from chromite) and decomposition of galena (or other primary lead minerals) are required for crocoite formation.

 

 

  

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trueblueminerals
trueblueminerals
rare large gemstones and minerals
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  • setillia
    setillia
    中性的

    Responsive seller, which is appreciated. Lovely gem. The only issue was with shipping. I paid for post but it was sent via Fedex. Fedex (of course) charged me illegal fees over a month after delivery! This was why I chose post and not Fedex.

  • olga22220
    olga22220
    积极的

    Paid and shipped - no feedback left after 100 days

  • hippu65
    hippu65
    积极的

    Been watching this for some time.. Got me a deal..! Great !

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有效期至
30th Nov 2024

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概述

列表类型 : Standard
产品编号 : 2244131
开始 : 12th November 2024 03:41 pm PST
* 所有价格均以:货币为单位