Mineralpedia Details for Pharmacosiderite
Pharmacosiderite
Named for the arsenic content after the Greek word farmaki, or pharmaki, meaning “poison,” and for its iron content after sideros, meaning “iron.” Somewhat common and widespread, Pharmacosiderite can be found in England, France, Germany, Slovakia, the USA, Namibia, and Australia. Pharmacosiderite is weakly piezoelectric, generated a charge in response to pressure, and pyroelectric, generates a charge in response to heat. Occurs as cubic crystals with diagonally striated faces most often are olive to emerald green sometimes amber to dark brown. Occurs as an oxidation product of arsenic-rich minerals in hydrothermal vein deposits and pegmatites. In pegmatites occupying decayed lollingite or arsenopyrite blades with Scorodite.
Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/pharmacosiderite.pdf
- Formula
- KFe3+4(AsO4)3(OH)4·6-7H2O
- Crystal System
- Isometric
- Crystal Habit
- Blocky, Crystalline - Coarse, Earthy
- Cleavage
- Indistinct, None, None
- Luster
- Adamantine - Resinous
- Color
- olive green, emerald green, reddish brown, yellowish brown, honey yellow
- Streak
- yellowish green
- Class
- Isometric - Hextetrahedral
- Fracture
- Brittle - Sectile
- Hardness
- 2.5
- WebMineral
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- Mindat
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Pharmacosiderite from Richmond Sitting Bull mine, Galena, Lawrence Co., South Dakota, United States
Bright emerald green cubic crystals to 2mm with elongated Scorodite.
