Ukususela kwinkqubo yokudubula, ukongeza i-ferric oxide, i-manganese dioxide yinkqubo yendabuko, emva kokusabela ngokwasemzimbeni nangokweekhemikhali, iya kwenza i-silicate ezinzileyo, umzimba womntu uphilile kwaye ukhuselekile; ukususela ekuzalweni kwezixhobo zodongwe phantse iminyaka engama-20 yembali, ayizange...
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