. Precious stones, a popular account of their characters, occurrence and applications, with an introduction to their determination, for mineralogists, lapidaries, jewellers, etc. With an appendix on pearls and coral. Precious stones; Pearls; Corals. 173 SYSTEMATIC DESCRIPTION OF PRECIOUS STONES hydro-phosphates, yttrium phosphates (sometimes containing titanic acid), diaspore, rutile, brookite, anatase, ilmenite, magnetite, cassiterite, red felspar, cinnabar, and gold. Garnet, and staurolite have also been observed here and recently euclase, but the last only as a rarity. Of these minerals, ca
. Precious stones, a popular account of their characters, occurrence and applications, with an introduction to their determination, for mineralogists, lapidaries, jewellers, etc. With an appendix on pearls and coral. Precious stones; Pearls; Corals. 173 SYSTEMATIC DESCRIPTION OF PRECIOUS STONES hydro-phosphates, yttrium phosphates (sometimes containing titanic acid), diaspore, rutile, brookite, anatase, ilmenite, magnetite, cassiterite, red felspar, cinnabar, and gold. Garnet, and staurolite have also been observed here and recently euclase, but the last only as a rarity. Of these minerals, cassiterite, felspar, and cinnabar have never been found in Minas Geraes in association with diamond. Schrauf argued from the occurrence of these minerals, and especially from the association together of tourmaline, garnet, zircon, staurolite, rutile, &c., that the rocks, from which have been derived the diamond-sands of the Serra da Chapada, were allied to the gneisses and syenites of southern Norway. It has been stated in descriptions of the geological structure of these mountains that they are built up of these particular rocks, but neither in this nor in other diamond districts in Bahia has any thorough geological investigation been made, and since the minerals associated with diamond are the Serra da Chapada. Fig. 36. Occurrence of diamond in the Serra da Cincord, Bahia. same in Bahia and in Minas Geraes, it is probable that the occurrence is also the same, namely, in itacolumite. Especially rich finds were made in the year 1844 in the Serra da Cincora (SincorA). This range is situated in longitude about 41° W. of Greenwich, and extends from south-west to north-east between latitudes 13° 15' and 12° 15' S. It forms the south-eastern spur of the Serra da Chapada (Fig. 36), with which it is connected at its southern end; it separates the basin of the Rio de Sao Francisco from that of the Rio Paraguassu, and constitutes the collecting-ground of these rivers. This range,
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