Hennomartinite , Quartz , Sugilite Locality: Wessels Mine (Wessel's Mine), Hotazel, Kalahari manganese fields, Northern Cape Province , South Africa ( Locality at mindat.org ) Size: miniature, 3.5 x 2.4 x 1.7 cm Hennomartinite and Sugilite in Quartz Beautiful specimen hosting a 1.5 cm gem quartz through which you see the sugilite matrix, studded also with minute crystals of (brown) Hennomartinite . RARE MATERIAL found only once at this mine! — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Hennomartinite
Hennomartinite is an IMA-recognized mineral species in the silicate class, with the chemical formula SrMn³⁺₂(Si₂O₇)(OH)₂·H₂O.
It crystallizes in the orthorhombic crystal system (space group P2_1cn). It is a member of the Lawsonite structural group.
Key properties: Mohs hardness 4; specific gravity 3.68; Vitreous luster; optically biaxial.
IMA symbol Hma, IMA status: approved, named in 1992.
From a hand specimen, in veinlets of s¶erandite-pectolite cutting sugilite, probably of hydrothermal origin in a bedded manganese deposit.
It is found associated with S¶erandite-pectolite, sugilite, braunite, taikanite, kornite.
The name refers to Henno Martin, German geologist, who has worked on the Precambrian geology of the general area where the mineral occurs.