NEOTOCITE

MnSiO₃.H₂O
Amorphous

Neotocite was reported from Franklin by Palache (1935), but has not been studied since. It is found at both deposits.

Description

Neotocite is apparently black, but is dark brown, with vitreous to resinous luster, no cleavage, and a hardness of 4 or less. It is very brittle and has a conchoidal fracture. The index of refraction is 1.57. It is easily identified by its luster, color, and brittleness.

Composition

Neotocite is a manganese silicate hydrate mineral. Only Sterling Hill neotocite has been analyzed yielding: SiO₂ 39.5, FeO 0.3, MgO 6.4, CaO 0.4, ZnO 0.6, MnO 37.2, As₂O₅ 1.0, with water by difference 14.6, total = 100.0 wt. %. Compared with some of the Swedish neotocites studied by Clark et al. (1978), this sample is highly magnesian. Sterling Hill material contains no appreciable carbonate, as evidenced by a lack of effervescence in 1:1 HCl.

Occurrence and paragenesis

Little is known of the occurrence of local neotocite. A studied Sterling Hill specimen consists of neotocite fracture-fillings in calcite. Palache (1935) reported neotocite in the marble from the Trotter Mine and also noted a neotocite associated with esperite. Hydrocarbons may be present. Unstudied neotocites are commonly associated with serpentine, rhodochrosite, and calcite; rhodonite may be the sole associated mineral.

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This page created: January 11, 2001