Zincite is one of the very few naturally occurring zinc oxide minerals, and natural specimens are essentially restricted to one place on Earth: Franklin and Sterling Hill, New Jersey. It is the namesake natural source of “ZnO” — the same compound now produced industrially in vast quantities.
Properties
- Formula: ZnO (often Mn-bearing)
- Crystal system: Hexagonal
- Hardness: 4 – 4.5
- Color: Deep red, orange-red, sometimes yellow
- Streak: Orange-yellow
- Luster: Sub-adamantine to greasy
- Cleavage: Perfect on {0001}
- Density: 5.6 g/cm³
Occurrence
Natural crystallized zincite is essentially a Franklin/Sterling Hill exclusive. Sharp hexagonal pyramids are extremely rare — most zincite occurs as cleavable masses in calcite. Synthetic zincite (smelter byproduct, Tarnowskie Góry, Poland) is widely available but is not natural.
Identification
Deep red color + orange-yellow streak + association with franklinite and willemite + Franklin source is essentially diagnostic. Distinguish from cuprite (cubic, similar red but different crystal system).
Collector Notes
Natural zincite crystals are among the rarest classical American collector minerals. Be aware: Polish “zincite” on the market is synthetic — only Franklin/Sterling Hill material is natural.
Found at these Localities
- Franklin and Sterling Hill (富兰克林矿(新泽西))
