Iko eriri a mụrụ na 1930s. Ọ bụ ụdị nke inorganic-abụghị dara ihe mepụtara pyrophyllite, quartz ájá, na nkume nzu, dolomite, calcite, brucite, boric acid, soda ash na ndị ọzọ na chemical ngwaọrụ. Ọ nwere ìhè arọ, elu ike, elu na ala okpomọkụ na-eguzogide, corrosio ...
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