Crocoite is a mineral consisting of lead chromate, PbCrO₄, and crystallizing in the monoclinic system. It is sometimes used as a paint, being identical in composition with the artificial product chrome yellow; it is the only chromate of any importance found in nature. It was discovered at Berezovsk near Ekaterinburg in the Urals in 1766; and named crocoise by F. S. Beudant in 1832, from the Greek if peoc, saffron, in allusion to its color, a name first altered to crocoisite and afterwards to crocoite. It is found as well-developed crystals of a bright hyacinth-red color, which are 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 Umtali in Mashonaland. Gold is often found associated with this mineral. Crystals far surpassing in beauty any previously known have been found in the Adelaide Mine at Dundas, Tasmania; they are long slender prisms, 3 or 4 in. in length, with a brilliant lustre and color. Crocoite is also the offical Tasmanian mineral emblem. General Name, Symbol, Number lead, Pb, 82 Chemical series poor metals Group, Period, Block 14, 6, p Appearance bluish white Atomic mass 207. ... A sample of ammonium dichromate Chromates and dichromates are salts of chromic acid and dichromic acid, respectively. ... In crystallography, the monoclinic crystal system is one of the 7 lattice point groups. ... Chrome Yellow is a natural yellow pigment made of lead chromate (PbCrO4). ... Ural may refer to one of the following: Ural Mountains Ural (region) Ural River Urals Federal District IMZ-Ural, a Russian motorcycle Ural automobile Ural, Krasnoyarsk Krai, an urban settlement in Russia This is a disambiguation page: a list of articles associated with the same title. ... François Sulpice Beudant (September 5, 1787 - December 10, 1850), French mineralogist and geologist, was born in Paris. ... Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ... Relative density (also known as specific gravity) is a measure of the density of a material. ... Quartz is amongst one of the most common minerals in the Earths continental crust. ... Quarrying granite for the Mormon Temple, Utah Territory. ... Gneiss Gneiss is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from preexisting formations that were originally either igneous or sedimentary rocks. ... Map of the Philippines showing the island groups of Luzon, Visayas, and Mindanao. ... General Name, Symbol, Number gold, Au, 79 Chemical series transition metals Group, Period, Block 11, 6, d Appearance metallic yellow Atomic mass 196. ... Emblems: Flora - Tasmanian Blue Gum Motto: Ubertas et Fidelitas (Fertility and Faithfulness) Slogan or Nickname: The Apple Isle; Holiday Isle Other Australian states and territories Capital Hobart Government Const. ...

Associated with crocoite at Berezovsk are the closely allied 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. Phoenicochroite, also known as Melanochroite is a mineral, a form of lead chromate, formula Pb2OCrO4. ... Vauquelinite is a complex mineral with the formula CuPb2CrO4PO4OH making it a combined chromate and phosphate of copper and lead. ...

References

• This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.

Encyclopædia Britannica, the 11th edition The Encyclopædia Britannica Eleventh Edition (1910–1911) is perhaps the most famous edition of the Encyclopædia Britannica. ... The public domain comprises the body of all creative works and other knowledge—writing, artwork, music, science, inventions, and others—in which no person or organization has any proprietary interest. ...

External links

• crocoite.com
• List of Tasmanian state emblems