Chemical composition -- Zinc oxide and manganese.
Color -- Dark red or yellowish-orange.
Optics -- R.I. 2.01-2.03. Uniaxial positive. Adamantine luster.
Durability -- Hardness 4-4.5. Brittle and heat sensitive with one direction of perfect cleavage. Not durable enough for use in jewelry.
Crystal structure -- Hexagonal.
Specific Gravity-- 5.68 (very dense).
Sources -- The only major locale is Frankin, New Jersey (USA). Faceted gems from this location are quite rare, and most are only a carat or two in weight. Despite its striking beauty, zincite remains a rare collector's item, due to its scarcity and difficulty in faceting.