Agates are semiprecious silica mineral, a variety of chalcedony that occurs in bands of varying color and transparency. Varieties are characterized by peculiarities in the shape and color of the bands, which are seen in sections cut at right angles to the layers. Agate is found throughout the world, commonly in cavities in eruptive rocks and in geodes. The middle picture above is an agate found in Mexico called Mexican Crazy Lace agate. The bottom picture above is a Montana Moss agate.
Amethyst is a transparent, coarse-grained variety of the silica mineral quartz that is valued as a semiprecious gem for its violet color. It contains more iron oxide than any other variety of quartz, and experts believe that its color arises from its iron content. Other theories attribute the color to contained manganese or hydrocarbons.
The name, derived from the Greek amethystos, “not intoxicated,” expresses the ancient folk belief that the stone protects its owner against drunkenness. In ancient writings the Latin name amethystus was used for amethyst, purple corundum, and purple garnet.
Apatite is any member of a series of phosphate minerals, the world’s major source of phosphorus, found as variously colored, glassy crystals, masses, or nodules.
Chalcedony is a very fine-grained variety of the silica mineral quartz usually bluish white, gray, yellow, or brown. In all ages chalcedony has been the stone most used by the gem engraver, and many colored varieties are still cut and polished as ornamental stones.
Labradorite is a feldspar mineral in the plagioclase series that is often valued as a gemstone and as ornamental material for its red, blue, or green iridescence. The mineral is usually gray or brown to black and need not be iridescent; when used as a gem it is usually cut as a cabochon (with a rounded convex surface). Labradorite is named for its occurrence near Nain, on the coast of Labrador, Canada.
The term “jade”refers to two different, yet similar semi-precious metamorphic mineral gemstones, Jadeite and Nephrite. Nephrite and jadeite are resistance to breakage and chipping and due to their toughness they made a superior weapons and tools for early man. Not until the 19th century that a French mineralogist determined that “jade” was in fact two different materials. Nephrite is usually only green and creamy white, while jadeite can have the full range of jades colours. Jade is mined in the regions of Canada, Australia, United States and Taiwan.
Jasper is an opaque, fine-grained or dense variety of the silica mineral chert that exhibits various colors. This variety, found in Madagascar, is normally tones of green and yellow.
Peridot, usually yellow-green to brownish-green; prized colors are distinctive deep yellow-greens of great uniformity. Transparent but often filled with small inclusions that may be minute black spinal crystals. Peridots can be found in New Mexico, and Chihuahua, Mexico. The principal source today is the San Carlos Indian Reservation in Arizona.
Shells are organic minerals composed of calcium carbonate . Throughout the history shells of many types and from many different kinds of animals have been popular as human adornments. They are often used whole and drilled so that they can be threaded. The intricate design and varying colour patterns of shells is mainly dependent on the diet of the animal the shell covers. Mother of pearl or nacre is created by mollusks such as oysters and abalones secreting a substances that consist of calcium carbonate. Nacre is continually deposited onto the inner surface of the animal’s shell creating the iridescent nacreous layer or mother of pearl. This is done both as a means to thicken, strengthen and smooth the inner surface of the shell. Mother of pearl has been used as decoration from buttons to inlays in furniture, jewellery and much more for thousands of years. Mother of Pearl can be found in many regions including Japan, Australia, Europe and the United States.
Tourmaline is one on the most complex gemstones of the silicate group and there are 10 different varieties created by the dozen or more elements they contain. Origin of name: from Sinhalese turamali = stone of mixed colours. There are Tourmalines, which change the colour from daylight to artificial light and others display chattoyance(a mobile, wavering striped reflection).Tourmaline is found in Africa, Brazil, Madagascar, Mexico, Myanmar, Namibia, Sri Lanka and USA.
Turquoise is hydrated copper and aluminum phosphate. It is a secondary mineral deposited from circulating waters, and it occurs chiefly in arid environments as blue to greenish, waxy veinlets in alumina-rich, weathered, volcanic, or sedimentary rocks. The color of turquoise ranges from blue through various shades of green to greenish and yellowish gray. Turquoise is opaque except in the thinnest splinters, takes a fair to good polish, and has a faintly waxy luster.