Pharmacosiderite

Pharmacosiderite
Pharmacosiderite
General
Category Arsenate minerals
Chemical formula KFe4(AsO4)3(OH)4·(6-7)H2O
Strunz classification 08.DK.10
Identification
Molar mass 873.38 g/mol
Color Greens, browns, Yellows
Crystal habit Massive to Crystalline
Crystal system Isometric - Hextetrahedral
Cleavage Distinct on the [100]
Fracture Brittle
Mohs scale hardness 2 1/2
Luster Adamantine
Streak yellowish green
Diaphaneity Subtransparent to subtranslucent
Density 2.9 g/cm³
Ultraviolet fluorescence None
References [1][2]

Pharmacosiderite is a hydrated basic ferric arsenate, with chemical formula KFe4(AsO4)3(OH)4·(6-7)H2O and a molecular weight of 873.38 g/mol. It consists of the elements arsenic, iron, hydrogen, potassium, sodium and oxygen. It has a Mohs hardness of 2 to 3, about that of a finger nail. Its specific gravity is about 2.7 to 2.9, has indistinct cleavage, and is usually transparent or translucent. It has a yellow or white streak and a yellow, green, brown or red color. Its lustre is adamantine, vitreous and resinous, and it has conchoidal, brittle and sectile fracture.

Pharmacosiderite has an isometric crystal system, with yellowish-green, sharply defined cube crystals. Its crystals are doubly refracting, and exhibit a banded structure in polarized light. When placed in ammonium solution, a crystal changes color to a distinguishing red. Upon placing it into dilute hydrochloric acid the original color is restored. This secondary origin mineral is normally formed in the oxidation zones of ore deposits. The alteration of arsenopyrite, tennantite and other primary arsenates can form pharmacosiderite. It can also form from precipitation of hydrothermal solutions, but only rarely. It can be found in abundance in Cornwall, Hungary and the U.S. state of Utah. When it was first discovered, pharmacosiderite was known as cube ore. The present name, given by J. F. L. Hausmann in 1813, is made up of the Greek words for arsenic and iron, the two most significant consisting elements. Farmakon means poison, which is related to arsenic, and sideros means iron. Pharmacolite and picropharmacolite, which are different arsenates, are not associated besides via nomenclature. Siderite, a carbonate mineral, only shares the common element iron with pharmacosiderite.

References

  1. ^ Pharmacosiderite: Pharmacosiderite mineral information and data
  2. ^ Pharmacosiderite Mineral Data

 This article incorporates text from a publication now in the public domainChisholm, Hugh, ed (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press. 


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Look at other dictionaries:

  • Pharmacosiderite — Phar ma*co*sid er*ite, n. [Gr. ? drug, poison + E. siderite.] (Min.) A hydrous arsenate of iron occurring in green or yellowish green cubic crystals; cube ore. [1913 Webster] …   The Collaborative International Dictionary of English

  • pharmacosidérite — ● pharmacosidérite nom féminin Arséniate hydraté naturel de fer, se présentant en cristaux vert foncé, de symétrie cubique …   Encyclopédie Universelle

  • pharmacosiderite —       hydrated iron arsenate mineral (KFe3+4(AsO4)3(OH)4·6−7H2O) that forms olive green to honey yellow, yellowish brown, and brown, transparent to translucent, striated cubes. It usually occurs as a weathering product of arsenic rich minerals,… …   Universalium

  • pharmacosiderite — noun A hydrated basic ferric arsenate, consisting of the elements arsenic, iron, hydrogen, potassium, sodium and oxygen …   Wiktionary

  • pharmacosidérite — (far ma ko si dé ri t ) s. f. Fer arséniaté associé aux filons d étain …   Dictionnaire de la Langue Française d'Émile Littré

  • pharmacosiderite — phar·ma·co·siderite …   English syllables

  • pharmacosiderite — | ̷ ̷ ̷ ̷ ̷ ̷ at pharmaco + noun Etymology: German pharmakosiderit, from pharmako pharmaco +siderit siderite : a mineral Fe3(AsO4)2(OH)3.5H2O consisting of a hydrous basic iron arsenate commonly occurring in green or yellowish green cubic… …   Useful english dictionary

  • Pharmakosiderit — Gelblicher Pharmakosiderit aus der Alto das Quelhas do Gestoso Mines, Gestoso, Portugal Chemische Formel KFe4(AsO4)(OH)4 · 7 H2O Mineralklasse …   Deutsch Wikipedia

  • List of minerals A-B (complete) — It is currently not possible to have a complete list of minerals . The International Mineralogical Association is the international group that recognises new minerals and new mineral names, however minerals discovered before 1959 did not go… …   Wikipedia

  • List of minerals N-R (complete) — It is currently not possible to have a complete list of minerals . The International Mineralogical Association is the international group that recognises new minerals and new mineral names, however minerals discovered before 1959 did not go… …   Wikipedia

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