Tridymite is a high-temperature polymorph of silica and usually occurs as minute tabular white or colorless pseudo-hexagonal crystals, or scales, in cavities...
9 KB (739 words) - 20:48, 24 January 2024
in α-tridymite it is in the range 154–171 pm. The Si–O–Si angle also varies between a low value of 140° in α-tridymite, up to 180° in β-tridymite. In α-quartz...
66 KB (6,935 words) - 15:03, 29 August 2024
with all the members of the quartz group, which also include coesite, tridymite and stishovite. It is named after Cerro San Cristóbal in Pachuca Municipality...
13 KB (1,335 words) - 21:39, 8 April 2024
appear to be closer to that of cristobalite and tridymite than to quartz. The structures of tridymite and cristobalite are closely related and can be...
56 KB (5,837 words) - 00:32, 6 September 2024
taken to avoid sudden temperature changes that may damage the crystals. Tridymite and cristobalite are high-temperature polymorphs of SiO2 that occur in...
61 KB (5,748 words) - 20:28, 3 September 2024
family). Examples include: 3D-Silicates, quartz family Quartz – SiO2 Tridymite – SiO2 Cristobalite – SiO2 Coesite – SiO2 Stishovite – SiO2 Moganite –...
20 KB (1,897 words) - 18:21, 16 July 2024
have rims of pigeonite. The groundmass contains interstitial quartz or tridymite or cristobalite. Olivine tholeiitic basalt has augite and orthopyroxene...
69 KB (7,809 words) - 04:19, 9 September 2024
of formation. The main three polymorphs are quartz, cristobalite, and tridymite. Quartz is the second most common mineral in the world (next to feldspar)...
46 KB (5,211 words) - 03:54, 8 September 2024
metallic cobalt and nickel and crystalline silica (quartz, cristobalite and tridymite). Usually, physical carcinogens must get inside the body (such as through...
185 KB (20,011 words) - 15:21, 24 August 2024
Pleochroism weak, from red-brown to green-brown Melting point 1670 °C (β tridymite) 1713 °C (β cristobalite) Solubility Insoluble at STP; 1 ppmmass at 400 °C...
6 KB (460 words) - 18:40, 21 March 2024
crystalline forms of silica, SiO2. The most important forms of silica include: α-quartz, β-quartz, tridymite, cristobalite, coesite, and stishovite....
46 KB (5,167 words) - 20:59, 8 September 2024
they consist of imperfect crystals of feldspar, mixed with quartz or tridymite; similar bodies are often produced artificially in glasses that are allowed...
22 KB (2,430 words) - 08:07, 20 May 2024
structure of interlocked six-member rings. This resembles the structure of tridymite, with aluminum substituting for every other silicon atom. This structure...
10 KB (970 words) - 15:11, 19 August 2024
extremely high pressure—stishovite, probably a pseudomorphosis after tridymite. From the article "First discovery of stishovite in an iron meteorite":...
10 KB (1,000 words) - 04:45, 1 September 2024
individual silicon and oxygen atoms to α-tridymite, similarly to the transition from α-quartz to β-quartz. β-tridymite slowly transforms to cubic β-cristobalite...
42 KB (5,607 words) - 22:19, 30 May 2024
rhyolites, and extremely Fe-rich olivine can exist stably with quartz and tridymite. In contrast, Mg-rich olivine does not occur stably with silica minerals...
30 KB (3,050 words) - 12:22, 1 August 2024
Commonly in most felsic ignimbrites the quartz polymorphs cristobalite and tridymite are usually found within the welded tuffs and breccias. In the majority...
23 KB (2,987 words) - 04:45, 18 July 2024
piezoelectric properties. When heated, crystalline AlPO4 (berlinite) converts to tridymite and cristobalite forms, and this mirrors the behaviour of silicon dioxide...
10 KB (852 words) - 14:03, 15 May 2024
example, quartz will change into a variety of its SiO2 polymorphs, such as tridymite and cristobalite at high temperatures, and coesite at high pressures....
109 KB (13,007 words) - 16:14, 20 July 2024
a web of minute feldspars mixed with interstitial grains of quartz or tridymite; but in many dacites it is largely vitreous, while in others it is felsitic...
17 KB (1,875 words) - 15:39, 25 August 2024
which form many polymorphs. Important ones include: α-quartz, β-quartz, tridymite, cristobalite, moganite, coesite, and stishovite. A classical example...
47 KB (5,143 words) - 03:32, 19 August 2024
Tourmaline (group of silicate minerals) Tranquillityite Tremolite Trevorite Tridymite Triphylite Triplite Triploidite Tripuhyite Troilite Trona Tschermakite...
42 KB (2,782 words) - 11:49, 1 September 2024
whereas in α-tridymite it ranges from 154–171 pm (6.1×10−9–6.7×10−9 in). The Si-O-Si bond angle also varies from 140° in α-tridymite to 144° in α-quartz...
58 KB (6,792 words) - 23:26, 9 September 2024
which are now classified as andesites. Quartz is rare in trachyte, but tridymite (which likewise consists of silica) is not uncommon. It is rarely in crystals...
19 KB (2,094 words) - 19:25, 8 July 2024
Tancoite Tco Telluroperite Tpr Thermaerogenite Tag Titanowodginite Twdg Tridymite Trd Tululite Tlu Taneyamalite Tny Telyushenkoite Tys Thermessaite Tms...
180 KB (418 words) - 05:15, 30 June 2024
in α-tridymite it ranges from 154 to 171 pm. The Si–O–Si bond angle also varies from 140° in α-tridymite to 144° in α-quartz to 180° in β-tridymite. In...
26 KB (3,278 words) - 21:12, 23 July 2024
form of silica composed mostly of bladed crystals of cristobalite and tridymite. Much opal-CT takes the form of lepispheres, which are clusters of bladed...
35 KB (4,216 words) - 13:52, 30 August 2024
Some of these lithophysae are several centimeters or more in diameter. Tridymite, fayalite and other minerals in the lithophysae may be precipitates from...
7 KB (874 words) - 20:29, 4 August 2024
graphite, ilmenite, merrillite, low-calcium pyroxene, schreibersite, tridymite and troilite. Glossary of meteoritics McSween, Harry Y. (1999). Meteorites...
3 KB (231 words) - 20:21, 10 September 2024
if present, may be rimmed by either of these calcium-poor pyroxenes. Tridymite or quartz may be present in the fine-grained groundmass of tholeiitic...
8 KB (883 words) - 14:20, 4 May 2024