Keilite is a mineral belonging to the silicate group, specifically within the olivine family. It is a relatively rare and lesser-known mineral found in mafic and ultramafic igneous rocks. The name "keilite" is derived from the German mineralogist Frantisek Keil, who first discovered it in the 1960s.
The chemical formula of keilite is MgFe3+2(SiO4)2O(OH), indicating its composition of magnesium (Mg), iron (Fe), silicon (Si), oxygen (O), and hydroxyl (OH). It typically occurs as small, translucent to opaque green crystals or grains, often alongside other minerals like pyroxene, olivine, and spinel.
Keilite is characterized by its tetragonal crystal structure, which gives it its distinct symmetry. It possesses excellent cleavage and exhibits vitreous to greasy luster on its surfaces. When observed under a polarizing microscope, it displays high birefringence, meaning it can split light into two rays and produce vivid interference colors.
In terms of its physical properties, keilite is relatively hard, registering a hardness of approximately 6.5 on the Mohs scale. Its specific gravity ranges from 3.67 to 3.76, indicating its density compared to water. Keilite is not known to have any significant industrial applications, primarily due to its rarity and limited occurrence. However, its scientific importance lies in studying the mineralogical compositions and processes of igneous rocks.
