異極礦

Hemimorphite — zinc's sky-blue signature

Hemimorphite is a zinc silicate from the oxidized upper zones of zinc ore bodies. Its name records a genuine crystallographic oddity: the crystals are hemimorphic — the two ends of a crystal have different faces — which also makes them pyroelectric, developing opposite electrical charges when heated.

Two very different looks

Collectors meet hemimorphite in two habits: glassy, colorless fan-shaped crystal sprays, and the botryoidal crusts whose saturated sky-blue color has made the species famous. The blue botryoidal material — including the Yunnan pieces we stock — owes its color to trace copper riding along in the zinc oxidation zone.

What to look for

On botryoidal material, color saturation and an unbroken, gently rolling crust surface set the grade. Combination pieces — hemimorphite with pink rhodochrosite or cobaltoan calcite from the same carbonate zones — carry a premium.

From our inventory

See the Yunnan locality page for our botryoidal blue material, or the calcite guide for its frequent companion species.

Hemimorphite in China

China is today the world's foremost source of botryoidal blue hemimorphite. The Wenshan Mine in Yunnan Province produces rounded, grape-like crusts of vivid sky-blue to robin's-egg-blue hemimorphite — the colour caused by traces of copper — over brown matrix, sometimes with aragonite or aurichalcite. Since the 1990s these Yunnan specimens have set the standard for the species and made Chinese hemimorphite a collector favourite worldwide.