endoteelinen

Endoteelinen is a rare silicate mineral characterized by a layered framework. It is typically described as a hydrated aluminosilicate containing modest amounts of magnesium and iron, with traces of alkali metals and calcium. The mineral displays a pale green to blue coloration and a vitreous luster. It crystallizes in the monoclinic system and commonly forms tabular to prismatic crystals that are translucent to opaque. Hardness on the Mohs scale ranges around 4 to 5. Endoteelinen exhibits perfect cleavage parallel to its layered plane and tends to occur in thin tabular aggregates.

It forms through low-grade metamorphic alteration of ultramafic rocks and serpentinites in subduction-zone settings, often associated with chlorite, serpentine, and talc. It is generally found in metamorphosed basalts and serpentinites, sometimes within hydrothermal veins. Its stability is limited at surface conditions and it tends to alter to clays and carbonates upon weathering.

The name Endoteelinen derives from the Endoteel region where the first specimens were reported by a research group in 2003. The term is proposed to reflect its internal layered structure; "endo" meaning within and "teelinen" reflecting the regional designation.

Because only a few specimens are known, Endoteelinen is primarily of interest to mineralogy as a window into layered silicate structures and metamorphic processes. Potential applications remain speculative, with research focusing on its crystal chemistry and potential catalytic properties under high-pressure conditions.