What is Scapolite?
Scapolite is a tetragonal framework silicate series, valued as a pale to yellow gemstone and as a collector mineral from metamorphic and alkaline rocks.
Mineralogy and crystal structure
Reference formula: (Na,Ca)4Al3(Al,Si)3Si6O24(Cl,CO3,SO4). Scapolite is a compositional series between marialite and meionite. The selected model is a representative scapolite structure; chlorine, carbonate and sulfate contents vary, so analysis and locality should accompany unusual material. Scapolite is classified with silicates and has a tetragonal crystal system. Typical hardness is 5.5–6 on the Mohs scale and specific gravity is approximately 2.5–2.8.
Colour, lustre and habit
Typical colours include colourless, white, yellow, pink, violet, grey. The usual prismatic, tabular, granular habit and vitreous, pearly lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Scapolite forms in or is associated with marbles, gneisses, skarns, pegmatites and alkaline igneous rocks. Important documented localities include Myanmar, Tanzania, Madagascar, Canada, Brazil and Norway.
A clear gem from a complex framework series
Scapolite offers a less familiar but commercially elegant alternative to other pale gems. Transparency, colour, chatoyancy and documented origin decide whether a piece belongs in jewellery or a mineral cabinet.
Collecting and care
Protect from impact and acids, and clean with mild soapy water. Avoid sudden heat in included or fractured gems.
