Teineite exhibited at the Mining Museum of Akita University — Photo: 掬茶 · CC BY-SA 4.0
Teineite
A blue copper tellurite — cerulean crystals from oxidized tellurium-bearing ores.
Intro adapted from Wikipedia (CC BY-SA).
Teineite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Cu²⁺(Te⁴⁺O₃)·2H₂O.
It crystallizes in the orthorhombic crystal system (space group P2_12_12_1).
Key properties: Mohs hardness 2.5; specific gravity 3.8; Pale blue streak; optically biaxial.
IMA symbol Tei, grandfathered status — known before the IMA’s founding, named in 1939.
A rare secondary mineral produced through oxidation of copper- and tellurium-bearing sulfides.
It is found associated with Tellurite, tellurium, pyrite, tetrahedrite, sphalerite, azurite, malachite, quartz, barite (Teine mine, Japan); hessite, galena, bornite, cerussite, azurite.
The name refers to the Teine mine, Japan, in which specimens were first found.