Jaffeite
Jaffeite is a relatively rare calcium silicate hydroxide mineral with the chemical formula Ca6(Si2O7)(OH)6. It crystallizes in the hexagonal crystal system, typically forming as microscopic, platy crystals or as massive aggregates.
It is often found in altered, calcium-rich skarns and within high-temperature, calcium-rich metamorphic rocks. Jaffeite can also occur in altered xenoliths within basaltic lavas.
Jaffeite is typically colorless or white, though it may exhibit slight tints of other colors due to impurities. Its hardness is approximately 3-4 on the Mohs scale, and it has a vitreous luster. Its streak is white.
The mineral was first described in 1977 for an occurrence at the Crestmore Quarry in Riverside County, California, USA. It is named in honor of Professor Howard W. Jaffe, an American mineralogist and petrologist.
Identifying jaffeite definitively usually requires X-ray diffraction or other advanced analytical techniques due to its small crystal size and similarities to other calcium silicate minerals.