Gleitums

Gleitums refers to a rare, hypothetical silicate mineral described in speculative geology and in some theoretical discussions of metamorphic petrology. The name is derived from the German gleiten, meaning to glide, chosen to reflect its proposed crystal habit with exceptionally smooth basal planes.

Gleitums crystals are typically colorless to pale blue, with a vitreous to pearly luster. It crystallizes in the monoclinic system, forms platy to blade-like crystals up to several millimeters, has a Mohs hardness around 4, and a characteristic low fracture resistance. The approximate chemical formula is (Mg,Fe)Si4O10(OH)2 with trace Al and Cr substituting for Mg.

It is described as forming under high-pressure, water-rich metamorphism in ultramafic rocks within subduction-zone environments, commonly associated with serpentine, talc, and quartz in vein networks.

Gleitums has been discussed as a potential marker mineral for certain metamorphic conditions and as a theoretical model for low-friction sheet silicates. No natural deposits are known to have been mined, and there are no established commercial applications.

In literature, Gleitums is sometimes cited in debates about mineral classification and the interpretation of metamorphic microstructures, illustrating how new minerals would be described if found.