Orange crystals of the extremely rare and new mineral alpeite (IMA 2016-072), a Mn vanadate of complex formula, from the type locality (Monte Alpe Mine, Genova Province, Liguria, Italy) and only one of the two known localities worldwide. — Photo: David Hospital · CC BY-SA 4.0
Alpeite
A rare calcium-manganese-magnesium silicate named for its type locality, the Monte Alpe mine in Italy.
Intro adapted from Wikipedia (CC BY-SA).
Alpeite is an IMA-recognized mineral species in the silicate class, with the chemical formula Ca₄Mn³⁺₂Al₂(Mn³⁺Mg)(SiO₄)₂(Si₃O₁₀)(VO₄)(OH)₆.
It crystallizes in the orthorhombic crystal system (space group Pnmm). It is a member of the Ardennite structural group.
Key properties: Mohs hardness 5.5–6; specific gravity 3.374; Beige streak; Vitreous luster; optically biaxial.
IMA symbol Apt, IMA status: approved, named in 2016.
A secondary mineral crystallized from V- and Mn-rich hydrothermal fluids along fractures during tectono-metamorphism.
It is found associated with Braunite, dolomite, quartz, todorokite, ganophyllite.
The name is derived from the locality, the Monte Alpe mine, that produced the first specimens.