Sussexite Locality: Sterling Mine, Sterling Hill , Ogdensburg , Franklin Mining District, Sussex County, New Jersey , USA ( Locality at mindat.org ) An attractive mass of waxy, lavender/pink sussexite, from the type locality for the species. This specimen is from the North Orebody portion of the mine. This material is very odd, and feels like talc when rubbed. 7 x 4 x 3.5 cm. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Sussexite
A pearly white-to-pink manganese borate forming fibrous monoclinic veins.
Intro adapted from Wikipedia (CC BY-SA).
Sussexite is an IMA-recognized mineral species in the borate class, with the chemical formula Mn²⁺BO₂(OH).
It crystallizes in the monoclinic crystal system (space group P2_1/c).
Key properties: Mohs hardness 3–3.5; specific gravity 3.3; White streak; Silky, dull, earthy luster; optically biaxial.
IMA symbol Ssx, grandfathered status — known before the IMA’s founding, named in 1868.
A rare hydrothermal mineral typically in veinlets in boron-bearing metamorphosed Mn–Fe–Zn deposits.
It is found associated with Pyrochroite, rhodochrosite, wiserite, hausmannite, sonolite, alabandite, seamanite, tephroite, alleghanyite, willemite, leucophoenicite, hauckite.
The name refers to Sussex Co., New Jersey, USA, within which the first specimens were collected.