Margarosanite Locality: Parker Shaft, Franklin, Sussex Co., New Jersey Size: miniature, 4.1 x 1.8 x 1.6 cm Margarosanite Small bits of the very rare margarosanite (fluorescent blue), embedded in nasonite, from this classic locality. From the Parker Shaft. Ex. John White Collection. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Margarosanite
Margarosanite is an IMA-recognized mineral species in the silicate class, with the chemical formula Ca₂PbSi₃O₉.
It crystallizes in the triclinic crystal system (space group P-1). It is a member of the Margarosanite structural group.
Key properties: Mohs hardness 2.5–3; specific gravity 3.99–4.33; White streak; Pearly on cleavage luster; optically biaxial.
IMA symbol Mga, grandfathered status — known before the IMA’s founding, named in 1916.
Found in a metamorphosed stratiform zinc deposit (Franklin, New Jersey, USA).
It is found associated with Nasonite, minehillite, almandine, hancockite, roeblingite, franklinite, willemite, rhodonite, manganaxinite, datolite, prehnite, manganoan biotite.
Its name comes from the Greek for pearl and tablet, in reference to its luster and lamellar habit.