Scapolite

Scapolite is a rather complex silicate with composition (Na,Ca)₄(Si,Al)₁₂O₂₄(Cl,CO₃,SO₄). The sample above left is about 4x9 cm and is from Frontenac County, Ontario. The gems above right are 12.3 and 288.1 carats and are from Burma. All these samples are displayed in the Smithsonian Museum of Natural History.