X-ray investigation of hillebrandite

Abstract

Hillebrandite was first characterized by Wright as a white, fibrous mineral with the composition 2CaO.SiO₂.H₂O, optical properties α_Na 1·605±0.005, γ_Na 1·612±0.003, moderately weak birefringence, parallel extinction, optic axial angle 2E between 60 and 80° and density 2.692. X-ray powder data were first published by Vigfusson, but these have not been substantiated by later investigators (Clark and Bunn, McMurdie and Flint, and Heller and Taylor). Synthetic dicalcium silicate β-hydrate has been found to resemble hillebrandite closely.