Neotocite, also known as Penwithite, is similar in composition to Serpentine and is an alteration product of Bementite. The chemical formula of Neotocite is (Mn2+Fe2+)SiO3 · H2O (Hydrated Manganese Iron Silicate) and its molecular weight is 149.26 gm. It is not a scarce mineral but rarely available as a faceted gem. Neotocite is always opaque and usually a shade of liver brown. Moh’s Hardness of Neotocite is 3.0 – 4.0.
Neotocite is found in many locations worldwide including Mitterdorf, Styria, Austria; Mont Saint-Hilaire, Rouville County, Québec, Canada; Valgraveglia Mine, Reppia, Graveglia Valley, Ne, Genova Province, Liguria, Italy; Noda-Tamagawa mine, Iwate Prefecture, Tohoku Region, Honshu Island, Japan; Lovozero Massif, Kola Peninsula, Murmanskaja Oblast’, Northern Region, Russia; Harstigen Mine, Pajsberg, Filipstad, Värmland, Sweden; and Franklin, Franklin Mining District, Sussex County, New Jersey, USA.
|Chemical Formula:||(Mn2+Fe2+)SiO3 · H2O|
|Hydrated Manganese Iron Silicate|
|Molecular Weight:||149.26 gm|
|Crystal Habit:||No crystals since it is Amorphous|
|Moh’s Hardness:||3.0 – 4.0|
|Density:||2.1 – 2.7 (g/cm3)|
|Color:||Black, dark Brown, liver Brown, Olive Green|
|Transparency:||Opaque, Translucent in thin fragments|
|Luster:||Dull to Resinous or Vitreous, may be slightly metallic|
|Refractive Index:||1.50 – 1.65 Isotropic|