Ludwigite Locality: Alta Stock, Salt Lake County, Utah, USA (Locality at mindat.org) Size: 8.9 x 6.1 x 3.8 cm. Ludwigite is a rare magnesium, iron borate and th — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Ludwigite
A magnesium-iron borate of contact-metamorphic and hydrothermal deposits.
Intro adapted from Wikipedia (CC BY-SA).
Ludwigite is an IMA-recognized mineral species in the borate class, with the chemical formula Mg₂Fe³⁺O₂(BO₃).
It crystallizes in the orthorhombic crystal system (space group Pbam). It is a member of the Ludwigite structural group.
Key properties: Mohs hardness 5; specific gravity 3.8; typically black or green; Black to greenish black streak; Submetallic. Streak: Black to greenish black. Luster: Silky luster; refractive index 1.888; optically biaxial.
IMA symbol Ldw, grandfathered status — known before the IMA’s founding, named in 1874.
Typically formed in magnesian iron skarn and contact metamorphic deposits.
It is found associated with Magnetite, forsterite, clinohumite, vonsenite, szaibélyite.
The mineral was named to honor Ernst Ludwig (1842–1915), Austrian Professor of Chemistry, University of Vienna, Vienna, Austria, who analyzed the original material.
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