A Quick Guide to Our Semi-Precious Gems

Agate is a name applied to an aggregate of various forms of silica, chiefly Chalcedony, found in the US, India, Morocco, the Czech Republic, Brazil, and Africa. Agates are 25-60 million years old.

Brazilian Agate
Brazilian Agate is mined from eroded lava beds in the Brazilian plateaus. Its rainbow colors are derived mainly from iron.

Crazy Lace or Mexican Agate
The whorl patterns in Crazy Lace Agate are embedded hematite and jasper. Mexico is the main source of this most unusual agate.

Montana Agate
Usually, Montana Agate is a translucent Moss Agate from Montana with pronounced dendritic forms.

Montezuma (Moctezuma) Agate
Montezuma is a misspelling of Moctezuma. This stone is usually small, very deeply weathered, and shows the peeling off of the outer bands.

Moss Agate
Moss Agate is characterized by tree-like, inclusions of Hornblende. These agates are often associated with the fertility of plants.

Polka-dot Agate
Polka-dot Agate is mined in Oregon and is peppered with distinctive black or yellow polka-dots.

Rio Puerco (Moss) Agate
This stone is of a red to apricot color with cloud-like moss, and it is found in Albuquerque.

Some Amber was deposited as long as one million years ago. As a sticky resin, it oozed from ancient pine trees and entrapped small insects, and bits of plants, feathers, and other material. Then, the resin was encased in dirt and debris, and, through a process of heat and pressure, it fossilized to become Amber.

Amethyst, a coarse-grained variety of the silica mineral quartz, is valued for its violet color. It is piezoelectric, which means that it is used in electronic applications. Amethyst is found in the US, Britain, Canada, Brazil, Mexico, Russia, Sri Lanka, Uruguay, East Africa, Siberia, and India.

Ammonites are an extinct group of marine animals in the phylum Mollusca and the class Cephalopoda. Their closest living relative is probably the modern nautilus, whom they resemble. Ammonites first appeared about 400 million years ago and became extinct around the time of the dinosaurs.

Citrine is a variety of quartz ranging in color from light yellow (its natural form), through orange, to a dark, reddish-brown (its heat-treated form). Most heat-treated Citrine comes from Brazil, whereas natural Citrine comes from Russia, France, and Madagascar.

Jasper, found world wide, is an opaque, impure variety of quartz that is usually red, yellow, or brown.

Picture Jasper
Picture jasper exhibits a number of variations in formation and impurities simultaneously, which results in what appear to be scenes or images in a cut section. Complex mixes of impurities produce wild color variations.

Ocean Jasper
Ocean Jasper is a type of Rhyolite, which is an igneous rock, rich in silica. Ocean Jasper has been found only along the northwest coast of Madagascar at the edge of the ocean where it can be seen and collected only at low tide.

Lapis, also called Lazurite, occurs in various shades of blue, some types being speckled with white calcite or yellow pyrite. It is not a mineral, but rather a rock colored by Lazurite. It is mined in Russia, Afghanistan, Chile, Italy, the US, Egypt, and the Middle East. Denim Lapis is of a slightly different color blue than Lapis Lazuli.

The Mabe Pearl is a cultured pearl from the oysters of French Polynesia (Tahiti). It is cultivated in an oyster called the Black-lipped Oyster, which is capable of producing green, black, and white pearls. These pearls are their natural color.

Opalized wood is simply wood that has been replaced by opal. Opal is not a true mineral, nor does it have a crystalline structure. Instead it is a compound of silica and water.

Peridot, pronounced pear-a-doe, is a yellowish-green gem variety of olivine. It is mined in Arizona, Burma, Norway, islands in the Red Sea, and Hawaii. Sometimes, it is found in meteorites. It has been mined for thousands of years and is said to have been Cleopatra’s favorite gem.

Petoskey stones were formed by the fossilization of an ancient coral, Heragonaria, which lived in the warm, shallow seas that covered Michigan during the Devonian, some 350 million years ago. The stones are found along the shore of lakes Michigan and Huron.

Petrified Wood is real wood that has been turned into stone. Volcanic ash, deposited on top of primitive conifers that fell into waterways, is a key ingredient in the petrification process. As the ash decomposed, it released chemicals that reacted with the wood to form quartz crystal, which. over millions of years, turned the wood into stone.

Palm wood stone comes from palm trees that lived during the Oligocene Epoch between 20 and 40 million years ago. The characteristic spotted look of palm wood is from the rod-like structures within the grain of the wood. Depending upon the angles of the cut, these structures show up as spots, tapering rods or lines.

Serpentine is composed of one or more of the three magnesium silicate minerals: lizardite, chrysotile, and antigorite. It is considered to be the metamorphosed remains of magnesium-rich igneous rocks from the earth’s mantle. It varies in color from apple green to black, and it is often mottled with light and dark colored areas.

Topaz is a gem-quality aluminum silicate mineral. It is transparent with a vitreous luster. Topaz crystals occur in highly acid igneous rocks and in metamorphic rocks. Important sources of topaz are in Russia, Siberia, Brazil, Australia, and Mexico and in New Hampshire, Colorado, and Utah in the US.

Turquoise, one of the oldest known gemstones, is composed chiefly of hydrated copper and aluminum phosphates. It is a secondary mineral deposited from circulating waters, and it occurs as granular veins running through a host rock. It varies in color from sky blue through various shades of green to greenish and yellowish gray.

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