Summary: Green calcium sulphosilicate layers were formed in lime-larnite-calcite wall coating in a lime kiln at Rivervale, Western Australia. The compound formed in the kiln flame area by the combination of siliceous lime sand feed with sulphur trioxide from the sulphurous oil fuel.

The calcium sulphosilicate is orthorhombic with a 10·183, b 15·408, c 6·825 Å, space group Pcmn. Crystals are [100] tablets or prisms elongated along c, D 2·95, hardness 5, streak pale green, decomposed by organic acids. Optical properties α 1·632 = [001] blue, β 1·638 = [100] yellow-green γ 1·640 yellow-green, 2Vα = 60°, dispersion r > v, X-ray powder lines: 2·855 (10) 032,202; 2·838 (7) 330,321; 3·35 (6) 012; 2·622 (6) 331; 2·571 (6) 060; 3·20 (5) 231; 1·962 (5); 1·899 (5); 1·896 (5); 1·372 (5).

Chemical analysis by P. Hewson gave: SiO₂ 21·50, Al₂O₃ 1·83, Fe₂O₂ 0·50, CO₂ 0·49, P₂O₅ 0·23, CaO 57·19, MgO 0·35, Na₂O 0·22, K₂O 0·22, SrO 0·15, Li₂O 0·06, SO₃ 16·71, H₂O⁺ 0·28, H₂O⁻ 0·10, others 0·04, total 99·87. On a water-free basis the unit cell contains Ca19·66Mg0·17Na0·14K0·08Sr0·03Li0·08S4·026−Si6·90Al0·78Fe0·123+C0·21P0·065−O47·71, approximately 4[Ca₅(SiO₄)₂SO₄] and isostructural with silicocarnotite, 4[Ca₅(PO₄)₂SiO₄]. Type material is preserved at the Government Chemical Laboratories, Perth, Western Australia.