FLINT GENUS. Conjiituent Parts. Alumina 74.5Q 82,47 Silica *5>5° Magnefia 8,25. OO 00 Oxyd of iron I,jO Chromic acid 6,18 Lime °>75 Lofs 2 >57 100,50 roo Klaproth, t. 2. p. 10. Vauquehn, N. 38. p. 89. Gcognosiic Situation. Werner is of opinion that it occurs in rocks be- longing to the neweft floetz trap formation. In the magnificent colleftion belonging to the Honourable Mr Grevilie are two interefting fpecimens which,’ al though they do not enable us to afcertain the repofi- tory of the fpinelle, make us acquainted with fom e of its accompanying foflils. In one of the fpecimens cryhals of fpinelle are imbedded in calcareous fpar» and accompanied with cryflals of mica, magnetic pyrites, and a fubflance which Count de Bournon be lieves to be afparagus ftone : in the other the fpinelle is
