Vermiculite is a naturally-occurring mineral composed of shiny flakes resembling Mica. In Mineralogical terms, it is hydrated laminar magnesium-aluminium-iron silicate It is produced in different grades or sizes. When heated to high temperature, vermiculite flakes expand 8-30 times its original size (exfoliation) and loses weight. Most applications for vermiculite use exfoliated material. It has been used in various industries for over 80 years, in construction, agricultural, horticultural and industrial markets. The main commercial producers are Brazil, China, South Africa, USA and Zimbabwe. Vermiculite mines are surface operations where ore is separated from other material, then screened or classified into several basic particle sizes.
The typical bulk density of crude vermiculite or vermiculite concentrate is in the range of 640-1120 kg/cubic metre. (40-70 lb/cubic foot) and exfoliated or expanded vermiculite is in the range of 64 – 160 kg/cubic metre (4 – 10 lb/cubic foot).