Also found in: Dictionary, Wikipedia.
a rock-forming mineral; a silicate containing calcium and magnesium, CaMg[SiO4], with frequent admixtures of Fe and Mn. Monticellite crystallizes in the orthorhombic system. It is similar in structure to minerals of the olivine group but has a larger unit cell.
Monticellite is colorless or gray. Its hardness on Mohs’ scale is 5–6, its density varies from 3,000 to 3,300 kg/m3 depending on the chemical composition, and its refractive index is 1.64–1.66. The mineral occurs as small crystals or grains in contactmetamorphic rocks of the sanidine facies and, less frequently, in alkaline igneous rocks.
Monticellite was named after the Italian mineralogist T. Monticelli (1759–1846).