Amethist
| ID | 253 | |
|---|---|---|
| Mineral | Amethist | |
| Location | Iraí - Rio Grande Do Sul - Brazil | |
| Fluorescence | LW-UV: close SW-UV: close |
|
| Mindat.org |
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|
Mindat data
| ID | 198 |
|---|---|
| Long ID | 1:1:198:0 |
| IMA Status |
0 1 |
| Variety of | 3337 |
| Entry type | 2 |
| Description | A violet to purple variety of quartz that owes its color to gamma irradiation (Berthelot, 1906) and the presence of traces of iron built into its crystal lattice (Holden, 1925). The irradiation causes the iron Fe(+3) atoms that replace Si in the lattic... |
| Other Occurrences | Very common, in many different environments. The commercially most important occurrences are in volcanic rocks, where amethyst crystals outline former gas cavities. In low and medium temperature hydrothermal veins associated with iron ores. As late overgrowth ("scepter quartz") on quartz in pegmatite and alpine-type environments. |
| Colour | Violet - purple |
| Hardness (min) | 7.0 |
| Hardness (max) | 7.0 |
| Lustre | Vitreous |
| About the name | From Greek "a-methystos", meaning not drunk. |
| Crystal System | Trigonal |
| ID | 1325 |
|---|---|
| Long ID | 1:1:1325:9 |
| Formula |
PbCu(AsO4)(OH)
|
| IMA Status |
0 1 |
| Occurrence | Oxidized zone of a polymetallic deposit. |
| Other Occurrences | Uncommon mineral in the oxidized zone of some polymetallic sulfide deposits. |
| Discovery Year | 1920 |
| Diapheny | Transparent,Translucent |
| Cleavage | Usually unobservable in botryoidal aggregates. |
| Tenacity | brittle |
| Colour | Olive-green, grey-green |
| Hardness (min) | 4.5 |
| Hardness (max) | 4.5 |
| Lustre | Vitreous |
| About the name |
Named by Otto Pufahl in 1920 for Gustav Bernhard Duft [b. 1859 Clausthal, Germany - 1924?], second General Manager of the Tsumcor Mine (Tsumeb Mine), Namibia (~1906), but Duft was active in Namibia as early as 1892. Guillemin (1956) distinguished two kinds of duftite: "duftite-α" = duftite (space group Pnam) and (Ca-bearing) "duftite-β" = duftite (space group P2 |
| Streak | Pale green, white |
| Crystal System | Orthorhombic |
| Cleavage Type | Poor/Indistinct |
| Fracture type | Conchoidal,Sub-Conchoidal |
| Morphology | Usually botryoidal, rare tiny crystals elongated [001] with curved and rough faces aggregated into crusts. Pseudo-octahedral. |
| UV | Not Fluorescent in UV |
| Comment Luster | Lustre vitreous on fracture surfaces; dull on crystal faces. |
| Publication Year | 1920 |
| key_elements |
0 1 2 |
| shortcode_ima | Dft |
| Group | Adelite-Descloizite Group |
Details
Price: € 20
Dimensions: Not registered
Weight: 644 g
Visibile in overview:
Notes:
| Symbol | Element | |
|---|---|---|
| As | Arsenic |
|
| Cu | Copper | |
| H | Hydrogen | |
| O | Oxygen | |
| Pb | Lead |
|
| Si | Silicium |