Rectangular-cut cuprian adamite, 0.73 cts, 4.9 x 4.1 mm, Laurion, Greece. © The Gem Trader. Used with permission.
Although adamite occurs in many localities, it’s very rarely cut as a gem. This mineral is much too soft and fragile for jewelry. However, collectors prize its intense fluorescence.
| Data | Value |
|---|---|
| Name | Adamite |
| Formula | Zn2(AsO4)OH + Co, Cu |
| Etymology | After Gilbert-Joseph Adam, the Parisian mineralogist who supplied the first specimens for study. |
| Occurrence | Secondary mineral in the oxidized zone of ore deposits. |
| Colors | Colorless; yellowish green, yellow in various shades (contains Fe); pale green, bluish green, green (contains Cu); rose and violet shades (color zoned, contains Co); purple (contains Mn). |
| Fracture | Subconchoidal to uneven |
| Hardness | 3.5 |
| Cleavage | Good 1 direction |
| Crystallography | Orthorhombic; crystals elongated or equant; druses, radial aggregates, and spheroids on matrix. |
| Refractive Index | 1.708-1.773 |
| Birefringence | See "Identifying Characteristics" below. |
| Dispersion | Strong |
| Luminescence | Intense green in SW, LW; also lemon yellow in SW. |
| Absorption Spectrum | Not diagnostic |
| Pleochroism | Colorless/ blue-green/yellow-green. Pale rose/ pale rose/ pale purple. Pink/ pale rose/colorless. |
| Optics | Biaxial (+/-); 2V = 15° (Cu. Var.) to 88°. See “Identifying Characteristics” below. |
| Optic Sign | Biaxial +, Biaxial - |
| Luminescence Present | Yes |
| Luminescence Type | UV-Long, UV-Short |
| Luster | Vitreous |
| Specific Gravity | 4.32-4.68 (red-violet) |
| Transparency | Translucent to transparent |
Cuprian adamite, Tsumeb, Namibia, on display at the Smithsonian National Museum of Natural History. Photo by thisisbossi. Licensed under CC By-SA 2.0.
Adamite forms a series, as the zinc (Zn) analogue, with olivenite, the copper (Cu) analogue. This series has a distinct, intermediate member known as zincolivenite. (Don’t confuse olivenite with olivine).
The presence of numerous impurities can create various colors in adamites. For example, iron (Fe) can cause yellow hues. Cuprian (Cu bearing) varieties show green hues. Cobalt (Co) bearing specimens can show rose or purple/violet hues. Manganoan or manganese (Mn) bearing specimens may have purple/violet colors as well as pink and lavender.
Manganoan adamite and lotharmeyerite, Ojuela Mine, Mapimí, Mun. de Mapimí, Durango, Mexico. Photo by Didier Descouens. Licensed under CC By-SA 3.0. (Lotharmeyerite occurs here as tiny, dark red crystals).
Adamites can have an intense green fluorescence under either shortwave (SW) or longwave (LW) ultraviolet light. They may also show lemon yellow fluorescence under SW.
This crystal specimen shows dozens of “pinwheel” adamites on gossan matrix with intense neon green fluorescence. Ojuela Mine, Mapimi, Durango, Mexico, 10.5 x 9.3 x 6.2 cm. © Rob Lavinsky, www.iRocks.com. Used with permission.
Due to wide variations in composition, optical properties can vary significantly.
| Locality |
α |
β |
γ |
Birefringence |
| Mapimi, Mexico (reddish) |
1.712 |
1.736 |
1.760 |
0.048 |
| Mapimi, Mexico (rose) |
1.710 |
1.735 |
1.759 |
0.049 |
| Mapimi, Mexico (violet) |
1.710 |
1.735 |
1.758 |
0.048 |
| Mapimi, Mexico (green) |
1.722 |
1.742 |
1.763 |
0.041 |
| Tsumeb, Namibia (Cu) |
1.742 |
1.768 |
1.773 |
0.031 |
| Tsumeb, Namibia (Co) |
1.722 |
1.738 |
1.761 |
0.039 |
| Laurium, Greece |
1.708 |
1.734 |
1.758 |
0.050 |
This cuprian Adamite crystal specimen also contains traces of cesium (Cs) as well as the rare-earth elements cerium (Ce) and dysprosium (Dy). Hilarion Mine, Laurium, Attiki Prefecture, Greece, 6.0 x 5.7 x 2.4 cm. © Rob Lavinsky, www.iRocks.com. Used with permission.
Scientists have used synthetic specimens of the adamite-olivenite series for spectroscopy research. However, there is no known jewelry use for this material.
None known.
Brilliant pear-cut cuprian adamite, 0.86 cts, 7.6 x 4.8 mm, Mapimi, Durango, Mexico. © The Gem Trader. Used with permission.
The Ojuela Mine in Mapimi, Mexico produces fine sprays of crystals in limonite matrix.
Tsumeb, Namibia also produces fine crystals, sometimes colored purple by cobalt.
Laurium, Greece yields specimens often containing copper, in lovely blue and green shades.
Other notable sources include:
Violet crystals, noted up to 1 cm long and transparent, would yield stones up to about 1-2 carats. Green material, usually not clean, would provide only small faceted gems (1-3 carats).
Adamites have a low hardness of 3.5 and good cleavage. Thus, they make less than optimal pieces for jewelry use. You’ll find these stones more likely in gem collections as crystal specimens than in jewelry collections. See our gemstone jewelry cleaning guide for care recommendations.
Adamite: Ojuela Mine, Mapimi, Mexico (0.86). Photo © Joel E. Arem, PhD, FGA. Used with permission.
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