What is Zincalstibite?
Zincalstibite is a rare colourless to white hydrated zinc aluminium antimonate of the cualstibite group, usually found in altered carbonate rocks and marble-associated deposits.
Mineralogy and structure
Reference formula: Zn2Al(OH)6[Sb(OH)6]. Zincalstibite is trigonal with ideal formula Zn2Al(OH)6[Sb(OH)6] and belongs to the hydrotalcite supergroup. Natural polytypism and hydration occur; COD 9010152 is used as a labelled representative model. Zincalstibite is classified with oxides and has trigonal crystal symmetry. Typical hardness is 2–3 on the Mohs scale and specific gravity is approximately 3.3–3.6.
Colour, lustre and habit
Typical colours include colourless, white, pale yellow. The usual tabular, botryoidal, crusty habit and vitreous lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Zincalstibite forms in or is associated with low-temperature alteration of antimony-bearing zinc deposits and carbonate-hosted metamorphic environments. Important documented localities include Carrara and the Apuan Alps in Italy, Switzerland, Austria and other European localities.
A quiet white mineral with layered antimony chemistry
Zincalstibite is a refined specialist specimen: its white appearance is understated, but the zinc-aluminium-antimony chemistry and marble locality make it memorable to informed buyers.
Collecting and care
Antimony-bearing and soft: avoid dust, grinding and acids, keep enclosed and wash hands after handling.
