Phosphosiderite

Phosphosiderite is a rare mineral named for its main components, phosphate and iron. The siderite at the end of phosphosiderite comes from "sideros", the Greek word for iron. It was discovered in 1890. It is mined in some parts of Chile, Argentina, Germany, Portugal, and the United States. It is totally soluble in Hydrochloric acid and nearly insoluble in nitric acid.[2][3] It is usually cut into a cabochon shape.[4] Phosphosiderite is known as “Piedrea voga” meaning pink stone or “La Roca Voca”, translating to pink rock in many other countries.[5] [6]

Phosphosiderite
Red phosphosiderite between violet strengite. Picture width 4 mm.
General
CategoryPhosphate minerals
Formula
(repeating unit)		hydrated iron phosphate FePO4•2H2O
Crystal systemMonoclinic
Crystal classPrismatic
Space groupP21/n (no. 14)
Identification
ColorUsually red to pink to purple, sometimes green, usually yellow veined
Crystal habittabular {010} or stout prismatic [001]
Twinningcommon on {101}, typically as interpenetration
Cleavage{010} Distinct, {001} Indistinct
Fractureuneven
Mohs scale hardness3.5–4
LusterVitreous
StreakWhite
DiaphaneityTransparent, translucent
Specific gravity2.74-2.76
Optical propertiesBiaxial
Refractive index1.692-1.739
Birefringence0.046
References[1]

Colors

The very fascinating, rare gemstone is often found in a bright orchid-purple tint with yellow-colored streaks. These vein-like streaks found in the stone are known as cacoxenite. The other rare color variants and the most precious ones are rose red, brown-reddish yellow, mossy green, and darker hues of purple. The most magnificent is the colorless variant of Phosphosiderite.[6]

References
  1. Taxer, K.; Bartl, H. (December 2004). "On the dimorphy between the variscite and clinovariscite group: refined finestructural relationship of strengite and clinostrengite, Fe(PO4). 2H2O". Crystal Research and Technology. 39 (12): 1080–1088. doi:10.1002/crat.200410293.
  2. "Phosphosiderite". National Gem Lab. 18 March 2017.
  3. Anthony et al, Handbook of Mineralogy (2001)
  4. "Phosphosiderite gemstone information". www.gemdat.org. Retrieved 2020-09-14.
  5. Houston, Diana. "Crystals and Jewelry". Crystals and Jewelry. Retrieved 2021-01-20.
  6. "Phosphosiderite - A Rare Gemstone - Its Characteristics and Properties". www.articlesfactory.com. Retrieved 2020-09-14.
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