Formula: Cu2(OH)3Cl

Colour: Mountain-green, bluish green to green; pale bluish green in transmitted light

Specific Gravity: 3.6

Crystal System: Monoclinic

Member of: Atacamite Group

Name: For the type locality, the Botallack Mine, St. Just, Cornwall.

Type Locality: Wheal Cock, Botallack Mine, Botallack, St Just, Cornwall, England, UK

Polymorph of: Atacamite, Clinoatacamite

A secondary copper mineral. May be confused with Kapellasite, which has a similar X-ray powder diffraction pattern. Some botallackites contain minor Zn, but the Zn:Cu ratio never approaches that of kapellasite (1:3).