Mineral Species: Tremolite var. Grammatite

Chemical Formula: Ca2Mg5Si8O22(OH)2

Chemical Name: Calcium Magnesium Silicate

Mineral Class: Inosilicate

Mineral Notes: Tremolite forms from the contact metamorphism of calcium-rich rocks. It is named after the Tremola Valley where it was first found. Tremolite belongs to the asbestos group of minerals, which means that the crystals are very thin, fibrous and separate easily. The excellent thermal insulation properties have been used in fire-proofing and other fire-retardant applications. Grammatite is a particulalry pure form of Tremolite lacking Iron, which is a common constituent of most other forms of Tremolite. Consequently the mineral is always white and forms fibrous crystals.

Description: The fibrous habit in this specimen of Tremolite can easily be seen. The individual crystals are long and fused into blocky-bundles which stretch the along the sides of the underlying white matrix. Others are embedded in the body of the matrix. The thinness of the crystals distorts light, producing a silk-like sheen.

Location: Campolungo, Kanton Tessin, Switzerland.