Putnisite
A strontium-calcium-chromium sulfate-carbonate discovered in 2007 on Western Australia's Polar Bear Peninsula.
Intro adapted from Wikipedia (CC BY-SA).
Putnisite is an IMA-recognized mineral species in the sulfate class, with the chemical formula SrCa₄Cr³⁺₈(CO₃)₈(SO₄)(OH)₁₆·25H₂O.
It crystallizes in the orthorhombic crystal system (space group Pnma).
Key properties: Mohs hardness 1.5–2; specific gravity 2.2; Pink streak; Vitreous luster; refractive index 1.578; optically biaxial.
IMA symbol Pni, IMA status: approved, named in 2011.
A product of the oxidation of a massive nickel sulfide deposit in komatiitic/dioritic rocks.
It is found associated with Quartz, a near-amorphous dark green mineral.
The mineral was named to honor Australian mineralogists Christine and Andrew Putnis of the Institut für Mineralogie, Universtität Münster, Germany.