Turquoise cabochon

The image shows a polished, rounded turquoise-colored cabochon with a brown/gold matrix or host-rock pattern. Turquoise is typically opaque, blue to blue-green, with a waxy to subvitreous luster and cryptocrystalline or microcrystalline structure. Mohs hardness is usually 5–6, specific gravity about 2.6–2.9, and cleavage is absent to indistinct. The brown matrix may consist of limonite, iron oxides, quartz, or altered host rock. The specimen may be stabilized or treated, which is common for commercial turquoise, but this cannot be confirmed from the image.

Turquoise forms in arid or semi-arid regions when copper-rich groundwater alters aluminum- and phosphate-bearing rocks, commonly near oxidized copper deposits. It is generally a secondary mineral formed at relatively shallow depths during weathering and hydrothermal alteration. Deposits range widely in age, from ancient Precambrian occurrences to younger Cenozoic deposits. The visible piece has been cut and polished, so it is a human-processed geological specimen rather than a natural rock surface.

Used primarily in jewelry, cabochons, beads, carvings, inlay, and ornamental objects. Historically it has been important in Egyptian, Persian, Native American, Tibetan, and Chinese jewelry traditions. Lower-grade material may be stabilized with resin to improve durability and color; dyed imitation materials also occur.

Turquoise is one of the oldest gemstones used by humans. Its color is controlled mainly by copper, while iron and dehydration can shift it toward green. The term 'matrix turquoise' refers to turquoise containing visible remnants of its host rock. Some apparent matrix may be natural, while webbing can also be artificially added or enhanced.

Identification clues include an opaque blue-green body color, brown or dark matrix, waxy luster, and moderate hardness. A genuine specimen should not show a glassy transparent appearance. A scratch test is generally not recommended on a finished cabochon; instead, examine an inconspicuous edge, feel its relatively low density, and use laboratory tests such as spectroscopy or specific-gravity testing if authenticity matters. Common sources include Iran (historically Persia), the southwestern United States—especially Arizona, Nevada, New Mexico, and California—Mexico, China, Chile, Tibet, and Australia. The bright uniform turquoise color and smooth polish are consistent with commercial jewelry-grade turquoise, though image-only identification cannot distinguish natural, stabilized, dyed, or reconstructed turquoise with certainty.