Stones | Crystal and stones

Garnets to Malachite

Group A. Isolates gems with a specific gravity of 4.7963 and over 4.70; in this group is placed zircon, with a specific gravity of from 4.70 to 4.88.

Group B. Stones whose specific gravity lies between 3.70 and under 4.7963.

Garnets, many varieties. Almandine 4.11 and occasionally to 4.25 Ruby 4.073 ” 4.080 Sapphire 4.049 [...]

Though the origin, formation, composition, characteristics and tests of each stone will be examined in detail when dealing with the stones seriatim, it is necessary to enquire into those particulars of origin which are common to all, in order thoroughly to understand why they differ from other non-metallic and metallic minerals.

At the very commencement [...]