Takovite
Takovite is a rare nickel carbonate mineral that belongs to the Hydrotalcite Group of minerals that also includes Stichtiteamong others. Takovite crystals are very rare and very small (less than 1 mm) so faceted gems come from opaque to translucent massive material from Lavrion District Mines, Lavrion District, Attikí Prefecture, Greece as seen in the picture above. This material has a beautiful bluish-green to green color but is very soft, with a Moh’s hardness of 2, and has a very low density.
Takovite was named for its discovery locality at Takovo, Gornji Milanovac, Moravica District, Serbia. It was discovered and named by Serbian geochemist Zoran J. Maksimović (1923- ) in 1955 and first described by him in 1957 in the Compte Rendu des Séances de la Société Serbe de Géologie (Minutes of Sessions of the Serbian Geological Society). Takovite was reinvestigated by mineralologists Dr. David L. Bish and Dr. George W. Brindley in 1977 on samples from the type locality and redefined and approved by the IMA.
Takovite distribution: from Takovo, Serbia. In the Blangvette West mine, Le Thoronet, Var, France. On Mueo, New Caledonia. In Western Australia, at the Carr Boyd Rocks nickel mine; the Agnew nickel deposit, north of Kalgoorlie; from Kambalda, 56 km south of Kalgoorlie; and the Dordie North nickel deposit. In the USA, at Wells Canyon, Oquirrh Mountains, Utah County, Utah, and at the Alpine mine, Clear Creek, San Benito County, California.
| Chemical Formula: | Ni6Al2(CO3OH)(OH)16 • 4(H2O) |
| Hydrated Nickel Aluminum Hydroxy-Carbonate | |
| Molecular Weight: | 799.54 gm |
| Composition: | Aluminum | 6.75 % | Al | 12.75 % | Al2O3 |
| Nickel | 44.04 % | Ni | 56.05 % | NiO | |
| Hydrogen | 3.06 % | H | 27.32 % | H2O | |
| Carbon | 1.13 % | C | 4.13 % | CO2 | |
| Oxygen | 45.02 % | O | |||
| 100.00 % | 100.25 % | = TOTAL OXIDE |
| Crystal Data | |
| Crystallography: | Trigonal – Hexagonal Scalenohedral |
| Crystal Habit: | (by analogy to the Hydrotalcite Group). Microcrystalline, platy, to 1 μm; commonly in veinlets and massive. |
| Twinning: | None |
| Cleavage: | n/a |
| Fracture: | n/a |
| Tenacity: | Brittle |
| Moh’s Hardness: | ~2.0 |
| Density: | 2.80 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Color: | Bluish green, yellowish green |
| Transparency: | Translucent to opaque |
| Luster: | n/a |
| Refractive Index: | 1.600 – 1.602 Uniaxial ( – ) |
| Birefringence: | 0.001 – 0.002 |
| Dispersion: | n/a |
| Pleochroism: | n/a |
