Warwickite (Field of view 3 mm) Locality: Nuestra Señora del Carmen Mines, La Celia, Jumilla, Murcia, Spain Original description: Brown Needles Warwickite on matrix; Photo and Collection Fernando Brederodes. — Photo: Fernando Brederodes · Public domain
Warwickite
A brown-black magnesium-iron-titanium borate of skarns and high-grade marbles.
Intro adapted from Wikipedia (CC BY-SA).
Warwickite is an IMA-recognized mineral species in the borate class, with the chemical formula (Mg,Ti,Fe,Cr,Al)₂O(BO₃).
It crystallizes in the orthorhombic crystal system (space group Pnam). It is a member of the Warwickite structural group.
Key properties: Mohs hardness 3.5–4; specific gravity 3.34–3.36; Bluish black streak; Subvitreous to pearly, submetallic on cleavages, commonly dull if altered luster; optically biaxial.
IMA symbol Wwk, grandfathered status — known before the IMA’s founding, named in 1838.
Found as a rare accessory mineral in boron-metasomatized limestone and associated skarns; in lamproitic rocks and carbonatitelike veinlets cutting them.
It is found associated with Chondrodite, szaibélyite, sinhalite, spinel, diopside, titanite, dravite, apatite, fluorite, scapolite, graphite, magnetite, ilmenite, pyrite, pyrrhotite.
The name refers to its first-noted occurrence near Warwick, New York, USA.