Gem Ore Identification

There are a handful of ways to identify gemstone ores.

Gems are the result of minerals developing over time, creating specific clear or colorful formations. There are different types of gems, including precious and semi-precious gemstones. Some gems offer distinct colors or appearances, while others are more difficult to properly identify.

Tools

There are a handful of tools that can prove to be beneficial in gem ore identification. Arm yourself with a specific gravity testing kit, microscope and slides, streak chart, cleavage chart, ceramic plate, hardness kit and a rock hammer for the best chance at gemstone identification. Each of these tools can help narrow down the type of gemstone you are dealing with. A gemstone identification field guide will also aid in the identification process.

Identifying Characteristics

Gemstones have a variety of distinct properties that lend themselves well to gemstone ore identification. Gemstones can be identified based on their colors, hardness, fracture and cleavage, diaphaneity, luster, specific gravity and other visual and tactile qualities. For example, talc has a greasy feel and flakes off when you rub it. Calcite has double refraction and breaks in rhombic-shaped pieces. Fluorite often has a fluorescent effect and a vitreous luster. Note every detail and characteristic that you see and feel, then use these details to identify the gemstone in question.

Hardness

Use the Moh's hardness scale to determine the gemstone's hardness. A hardness kit will simplify this process by containing minerals representing each of the Moh's hardness scale levels. Attempt to scratch the unidentified gemstone using each of the test minerals until the gemstone is successfully scratched, indicating its hardness level. Emerald has a hardness of between 7.5 and 8, for example, and diamond has a hardness of 10.

Cleavage

Crystals and gemstones have a tendency to break in specific ways, which is known as cleavage. Look for cleavage in your gemstone, or strike it with a hammer and examine the subsequent breakage. Compare these details with the details of a cleavage chart to help narrow down its identification. The cleavage in mica is a perfect basal cleavage, while an emerald's cleavage is imperfect.

Ceramic Test

You can use a streak chart and ceramic tile to help identify your gemstone ore. Rub the gemstone on a ceramic plate and compare the resulting streak to a streak chart. Not all gemstones will leave such a streak, but many can. Obtain a streak testing kit from a geology supply store to get the right ceramic plate and an identification chart.

References

• Geology: Art's Mineral Identification Chart
• All Color Gemstones: Steps to Identify Gem Stones!