☞ In mineralogical chemistry the silicates include; the unisilicates or orthosilicates, salts of orthosilicic acid; the bisilicates or metasilicates, salts of metasilicic acid; the polysilicates or acid silicates, salts of the polysilicic acids; the basic silicates or subsilicates, in which the equivalent of base is greater than would be required to neutralize the acid; and the hydrous silicates, including the zeolites and many hydrated decomposition products.