Amethist and Quartz
| ID | 203 | |
|---|---|---|
| Mineral |
Amethist
Quartz |
|
| Location | Rio Grande do Sul - Brazil | |
| Fluorescence | LW-UV: close SW-UV: close |
|
| Mindat.org |
View Amethist information at mindat.org View Quartz information at mindat.org |
|
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 | 3337 |
|---|---|
| Long ID | 1:1:3337:0 |
| Formula |
SiO2
|
| IMA Status |
0 1 |
| Other Occurrences | Most of them... |
| Industrial | Ore for silicon, glassmaking, frequency standards, optical instruments, silica source for concrete setting, filtering agents as sand. A major component of sand. |
| Diapheny | Transparent,Translucent |
| Cleavage |
The rhombohedral cleavage r |
| Tenacity | brittle |
| Colour | Colorless, purple, rose, red, black, yellow, brown, green, blue, orange, etc. |
| Hardness (min) | 7.0 |
| Hardness (max) | 7.0 |
| Luminescence | Triboluminescent |
| Lustre | Vitreous |
| About the name | Quartz has been known and appreciated since pre-historic times. The most ancient name known is recorded by Theophrastus in about 300-325 BCE, κρύσταλλος or kristallos. The varietal names, rock crystal and bergcrystal, preserve the ancient usage. The root words κρύοσ signifying ice cold and στέλλειυ to contract (or solidify) suggest the ancient belief that kristallos was permanently solidified ice. The earliest printed use of "querz" was anonymously published in 1505, but attributed to a physician in Freiberg, Germany, Ulrich Rülein von Kalbe (a.k.a. Rülein von Calw, 1527). Agricola used the spelling "quarzum" (Agricola 1530) as well as "querze", but Agricola also referred to "crystallum", "silicum", "silex", and silice". Tomkeieff (1941) suggested an etymology for quartz: "The Saxon miners called large veins - Gänge, and the small cross veins or stringers - Querklüfte. The name ore (Erz, Ertz) was applied to the metallic minerals, the gangue or to the vein material as a whole. In the Erzgebirge, silver ore is frequently found in small cross veins composed of silica. It may be that this ore was called by the Saxon miners 'Querkluftertz' or the cross-vein-ore. Such a clumsy word as 'Querkluftertz' could easily be condensed to 'Querertz' and then to 'Quertz', and eventually become 'Quarz' in German, 'quarzum' in Latin and 'quartz' in English." Tomkeieff (1941, q.v.) noted that "quarz", in its various spellings, was not used by other noted contemporary authors. "Quarz" was used in later literature referring to the Saxony mining district, but seldom elsewhere. Gradually, there were more references to quartz: E. Brown in 1685 and Johan Gottschalk Wallerius in 1747. In 1669, Nicolaus Steno (Niels Steensen) obliquely formulated the concept of the constancy of interfacial angles in the caption of an illustration of quartz crystals. He referred to them as "cristallus" and "crystallus montium". Tomkeieff (1941) also noted that Erasmus Bartholinus (1669) used the various spellings for "crystal" to signify other species than quartz and that crystal could refer to other "angulata corpora" (bodies with angles): "In any case in the second half of the XVIIIth century quartz became established as a name of a particular mineral and the name crystal became a generic term synonymous with the old term 'corpus angulatum'." |
| Streak | White |
| Crystal System | Trigonal |
| Cleavage Type | Poor/Indistinct |
| Fracture type | Conchoidal |
| Twinning | Dauphiné law. Brazil law. Japan law. Others for beta-quartz... |
| Thermal Behaviour | Transforms to beta-quartz at 573° C and 1 bar (100 kPa) pressure. |
| shortcode_ima | Qz |
Details
Price: € 15
Dimensions: Not registered
Weight: 599 g
Visibile in overview:
Notes:
| Symbol | Element | |
|---|---|---|
| O | Oxygen | |
| Si | Silicium |