430 CLAY FAMILY. Water, Carbonate of Lime, 2.0 Oxide of Iron, with Silica. Constituent Parts. 98.0 94.0 5.0 91.00 6 00 2.00 Alumina. 0.5 100.0 99.5 Vaquelin, in Hauy’s Bucholz, in Leonhard’s Min. t. ii. p. 432. Min. Taschenb. for 1812, s. 5. & 8. Geognostic and Geographic Situations. It has hitherto been found only at St Oien, in the vicinity of Paris, the Spanish localities given by some mineralogists being erroneous. It occurs, aldhg with flint, in floetz limestone, and somstimes contains petri factions of the same species as those found in flint. Dr Schneider has shewn that there is an uninterrupted transi tion from flint into floatstone, in such a manner, that the centre ot a mass will be pure and solid flint, but becomes gradually more porous as we approach the surface, when it passes into floatstone. Hence, this mineral may or, a general view, be considered as an uncommonly vesicular or porous flint; and it would be an improvement in the arrangement, to follow the method of Karsten and Stef- lens, to place it beside flint. XII. CLAY-
