Most potting composts contain a combination of peat and vermiculite or perlite. Aggregates are generally "Sphagnum" (peat moss), sand, and perlite or vermiculite. A common medium used is 'peat-lite', a mixture of peat moss, vermiculite, and perlite. It is sometimes mixed with lightweight aggregates, such as perlite or vermiculite. Some vermiculite exfoliators blend with lower-cost perlite also. Water glass is a useful binder of solids, such as vermiculite and perlite. The fill material is typically soil, loam, sand, vermiculite, other mineral fragments or sawdust. Numerous people were knowingly exposed to the harmful dust of vermiculite that contained asbestos. Some deposits of vermiculite have been found to be contaminated with small amounts of asbestos. This spawn is the mushrooms mycelium and will colonize the coir/vermiculite mix eventually fruiting mushrooms. Pure vermiculite does not contain asbestos and is non-toxic. The coir is usually mixed with vermiculite and pasteurised with boiling water. Apatite, barite and vermiculite are among the industrially important minerals associated with some carbonatites. Disposable heat packs typically contain cellulose, iron, water, activated carbon, vermiculite, and salt. They may also be sources of mica or vermiculite.