Putnisite is a mineral composed of strontium, calcium, chromium, sulfur, carbon, oxygen and hydrogen. It was discovered on the Polar Bear Peninsula in Shire of Dundas, Western Australia in 2007 during mining activity. Following identification and recognition by the IMA in 2012 the mineral was named after mineralogists Andrew and Christine Putnis.
|Crystal class||Dipyramidal (mmm) |
H-M symbol: (2/m 2/m 2/m)
|Unit cell||a = 15.351 Å, |
b = 20.421 Å,
c = 18.270 Å; Z = 4
|Crystal habit||Pseudocubic crystals|
|Cleavage||,  and  good|
|Fracture||Brittle - uneven|
|Mohs scale hardness||1.5-2|
|Optical properties||Biaxial (–)|
|Refractive index||nα = 1.552, nβ = 1.583 and nγ = 1.599|
|Pleochroism||Distinct: X pale bluish grey, Y pale purple, Z pale purple|
Putnisite has unique chemical and structural properties, and does not appear to be related to any of the existing mineralogical families. Crystals are translucent purple, but show distinct pleochroism (from pale purple to pale bluish grey, depending on the angle of observation) and leave pink streaks when rubbed on a flat surface.
- "New Mineral Shows Nature's Infinite Variability". University of Adelaide. Retrieved 26 April 2014.
- "Putnisite". Mineralogical Magazine. Retrieved 26 April 2014.
- "Putnisite: Putnisite mineral information and data". Mindat.org. 2014-04-07. Retrieved 2014-04-29.