:Dark Neotocite with bright Cuprite. JSS specimen and photo. Locality: Milpillas Mine, Cuitaca, Mun. de Santa Cruz, Sonora, Mexico — Photo: John Sobolewski · CC BY 3.0
Neotocite
Neotocite is an IMA-recognized mineral species in the silicate class, with the chemical formula (Mn,Fe)SiO₃·H₂O.
It crystallizes in the amorphous crystal system. It is a member of the Allophane structural group.
Key properties: Mohs hardness 3–4; specific gravity 2.1–2.7; Dark brown to black streak; Dull to resinous or vitreous, may be feebly metallic luster; optically isotropic.
IMA symbol Neo, grandfathered status — known before the IMA’s founding, named in 1849.
An alteration product of manganese-bearing silicate minerals.
It is found associated with Rhodonite, calcite, quartz.
The name comes from the Greek, meaning of recent origin, as it is an alteration product.