Carnelian to Lapis-Lazuli

Carnelian is a reddish variety of chalcedony, merging into greyish red, yellow, and brown; it is translucent, like horn. Carnelian takes a high polish and its colours are sometimes heightened by exposure to the sun or by heat. This attractive semi-precious stone was formerly much more extensively used than now, and its merits may, through the vagaries of fancy and fashion, which govern the fates of all gems, again raise it higher in popular favour.

Chondronite, a mineral that is found abundantly at the Tilly Foster mine in Brewster, Putnam County, New York, appears in deep garnet-red crystals of great beauty. Chondronite is classed with the minor gems, and it deserves a more extensive use. Hardness, 6.5. It has a vitreous lustre.

Diopside is a variety of pyroxene; hardness, 5 to 6; lustre, vitreous or greasy; transparent to translucent; and doubly refractive. Fine specimens, fit for gem purposes, are found near DeKalb, St. Lawrence County, New York. When cut brilliant, diopside makes a very attractive stone and resembles green tourmaline.

Dioptase is a silicate of copper; other names for it are achirite and Congo emerald; hardness, 5. The softness and brittleness of this attractive stone disqualify it for extensive use.

Fluorite or fluorspar, of which chlorophane or cobra stone is a variety, is a highly lustrous, brittle crystal of wide colour range; hardness, 4. Varieties of fluorspar are sometimes termed, in the trade, "false" ruby, emerald, sapphire, and other well-known gem stones.

Gold-Quartz—in crystals, filiform, reticulated, and arborescent shapes—is commonly worn as a jewel. Gold penetrating white, black, rose, and amethystine quartz, is worked into jewelry of all sorts, sometimes of very elaborate designs. These uses of gold-quartz are most common on the Pacific coast and in western North American cities.

Hematite, composed of iron 70, oxygen 30, is commonly cut into beads, charms, and intaglios. Chromic iron and ilmenite are similarly used. Although this iron ore is steel-grey, when polished, its streak, when scratched, is red; hence the name hematite, meaning "bloodstone."

Iolite, also called dichroite and water sapphire, is a pleochroic mineral occasionally cut for gem purposes. It is somewhat harder than quartz.

Jet is a soft compact light coal of a lustrous velvet black colour, and can be highly polished. It is used not polished for mourning goods. Jet was the agates of the ancients, their source of supply being near the river Gagas in Syria, from which the name of the mineral was derived.

Labradorite, sometimes, in the trade, called labrador, is a feldspar. Because of its structure some of the varieties of labradorite reveal a wonderful variety of colours. Labradorite can be highly polished and exhibits beautiful chatoyant reflections.

Lapis-Lazuli was long regarded as a separate specific mineral; it was the sapphire of the Greeks, Romans, and the Hebrew Scriptures. Instead of being a simple mineral, lapis-lazuli consists of a bluish substance (lazurite) with granular calcite, scapolite, diopside, amphibole mica, pyrite, etc. The hardness of lapis-lazuli is 5.5; specific gravity, about 2 to 4; lustre, vitreous; translucent to opaque.