THALCUSITE Meaning and
Definition
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Thalcusite is a rare mineral that occurs in the form of small, thin, tabular crystals. It belongs to the silicate mineral group and specifically to the epidote group. The mineral contains a combination of elements including calcium, iron, aluminum, and silicon, with the empirical formula CaAl2(AlSiO4)(Si2O7)(OH). Thalcusite has a distinct brown coloration, often varying from light yellow-brown to dark brown, and features a vitreous to resinous luster.
Thalcusite is typically found in metamorphic rocks, particularly those that have undergone low-grade regional metamorphism. It commonly forms within shear zones, where rocks have been subjected to high temperatures and pressures. The mineral can also occur in granite or shale, and it is occasionally found in association with other minerals such as garnet and tremolite.
In terms of physical properties, thalcusite has a hardness of 6 to 7 on the Mohs scale, indicating its relatively high resistance to scratching. It has a monoclinic crystal system and displays perfect cleavage in one direction, making it easy to split the crystals along flat planes. Thalcusite is not known to have any significant industrial uses, but its unique crystal structure and occurrence in certain geological settings make it of interest to mineral collectors and scientists studying metamorphic processes.
