Putnisite is a newly discovered mineral that occurs as tiny crystals on volcanic rock. One such crystal, just 0.4 millimeters across, shown here, was recently found at the Armstrong mine in Widgiemooltha, Western Australia.
Credit: Peter Elliott
A new purple-pink mineral that has a chemical composition and crystalline structure unlike any of the known 4,000 minerals has been discovered at a mining site in Western Australia, researchers report.At times you would think that everything that could be discovered has already been found. Then you come across something like this. I took a mineralogy course in college, but about all I can do is identify quartz, feldspar and mica in some rocks.
Now called putnisite, the mineral was discovered in a surface outcrop of Polar Bear Peninsula, Southern Lake Cowan, north of Norseman. While workers with a mining company were prospecting for nickel and gold, one of them noticed the bright-pink grains and sent the mineral to the Commonwealth Scientific and Industrial Research Organization (CSIRO), and then it was sent to Peter Elliott, a research associate with the South Australian Museum, for examination....
And, sure enough, the crystal was novel.
Elliott added, "Putnisite, a strontium calcium chromium sulfate carbonate, has both a unique chemical composition and a unique crystal structure." (The color of putnisite crystals ranges from pale to dark purple, with a pink streak, according to the researchers.)
Found on volcanic rock, the new mineral occurs as tiny crystals just 0.02 inches (0.5 millimeters) in diameter, and looks like spots of dark pink on dark-green-and-white rock; under a microscope, the mineral appears as cubelike crystals.
"When the rocks in the Lake Cowan area were deposited millions of years ago, they contained small concentrations of strontium calcium chromium and sulfur," Elliott said. "Over time, weathering released these elements and concentrated them, allowing putnisite to crystallize."