Paragonite
| Paragonite | |
|---|---|
 Paragonite with garnet | |
| General | |
| Category | Phyllosilicate minerals |
| Group | Mica group, dioctahedral mica group |
| Formula | NaAl2(AlSi3O10)(OH)2 |
| IMA symbol | Pg[1] |
| Strunz classification | 9.EC.15 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | C2/c |
| Identification | |
| Color | Colorless, pale yellow, grayish, grayish white, greenish, light apple-green |
| Crystal habit | massive, fibrous or scaly |
| Twinning | common on the [310] less common on the {001} |
| Cleavage | Perfect on the {001} |
| Fracture | Micaeous |
| Tenacity | Elastic |
| Mohs scale hardness | 2.5–3 |
| Luster | Pearly |
| Streak | White |
| Diaphaneity | transparent to translucent |
| Specific gravity | 2.78 |
| Optical properties | Biaxial (−) |
| Refractive index | nα = 1.564 – 1.580 nβ = 1.594 – 1.609 nγ = 1.600 – 1.609 |
| Birefringence | δ = 0.036 |
| Dispersion | r < v strong |
| Ultraviolet fluorescence | None |
| References | [2][3][4][5] |
Paragonite is a mineral, related to muscovite. Its empirical formula is NaAl2(AlSi3O10)(OH)2. A wide solvus separates muscovite from paragonite, such that there is little solid solution along the vector[clarification needed] Na+K+ and apparent micas of intermediate composition is most commonly a microscopic (or even sub-microscopic) intergrowth of two distinct micas, one rich in K, and the other in Na. Paragonite is a common mineral in rocks metamorphosed under blueschist facies conditions along with other sodic minerals such as albite, jadeite and glaucophane. During the transition from blueschist to greenschist facies, paragonite and glaucophane are transformed into chlorite and albite.[6] Jadeite bearing pyroxene minerals have suggested clinozoisite and paragonite are associated and derived from lawsonite releasing quartz and water via the following reaction:[7]
![{\displaystyle {4\,\mathrm {CaAl} {\vphantom {A}}_{\smash[{t}]{2}}\mathrm {Si} {\vphantom {A}}_{\smash[{t}]{2}}\mathrm {O} {\vphantom {A}}_{\smash[{t}]{8}}(\mathrm {H} {\vphantom {A}}_{\smash[{t}]{2}}\mathrm {O} ){\vphantom {A}}_{\smash[{t}]{2}}{}+{}\mathrm {NaAlSi} {\vphantom {A}}_{\smash[{t}]{2}}\mathrm {O} {\vphantom {A}}_{\smash[{t}]{6}}{}\mathrel {\longrightleftharpoons } {}2\,\mathrm {Ca} {\vphantom {A}}_{\smash[{t}]{2}}\mathrm {Al} {\vphantom {A}}_{\smash[{t}]{3}}\mathrm {Si} {\vphantom {A}}_{\smash[{t}]{3}}\mathrm {O} {\vphantom {A}}_{\smash[{t}]{12}}(\mathrm {OH} ){}+{}\mathrm {NaAl} {\vphantom {A}}_{\smash[{t}]{3}}\mathrm {Si} {\vphantom {A}}_{\smash[{t}]{3}}\mathrm {O} {\vphantom {A}}_{\smash[{t}]{10}}(\mathrm {OH} ){\vphantom {A}}_{\smash[{t}]{2}}{}+{}\mathrm {SiO} {\vphantom {A}}_{\smash[{t}]{2}}{}+{}6\,\mathrm {H} {\vphantom {A}}_{\smash[{t}]{2}}\mathrm {O} }}](https://wikimedia.org/api/rest_v1/media/math/render/svg/f171dcd4948f9f96867f1c867f252bc3174101ab)
It was first described in 1843 for an occurrence at Mt. Campione, Tessin, Switzerland.[4] The name derives from the Greek, paragon, for misleading, due to its similar appearance to talc.[5]
See also
References
- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ Mineralienatlas
- ^ Mindat
- ^ a b Webmineral
- ^ a b Handbook of Mineralogy
- ^ Deer, W. A.; et al. (2006). Rock-forming minerals, Volume 3A Micas (2 ed.). Geological Society of London. p. 302. ISBN 978-1-86239-142-0.
- ^ Deer, William A. (1997). Single-chain Silicates, Volume 2A. Geological Society of London. p. 477.
 | This article about a specific silicate mineral is a stub. You can help Wikipedia by adding missing information. |
Content Disclaimer
Informasi ini disarikan dari Wikipedia dan disajikan kembali untuk tujuan edukasi. Konten tersedia di bawah lisensi CC BY-SA 3.0. Kami tidak bertanggung jawab atas ketidakakuratan data yang bersumber dari kontribusi publik tersebut.
- The information displayed on this website is sourced in part or in whole from Wikipedia and has been adapted for the purpose of restating it. We strive to provide accurate and relevant information, however:
- There is no guarantee of absolute accuracy. Wikipedia is an open, collaborative project that can be edited by anyone, so information is subject to change.
- It is not intended to constitute professional advice. The content displayed is for informational and educational purposes only. For important decisions (e.g., medical, legal, or financial), please consult a professional.
- Content copyright. Wikipedia is licensed under the Creative Commons Attribution-ShareAlike License (CC BY-SA). This means that content may be reused with appropriate attribution and shared under a similar license.
- Responsible use. Any risk arising from the use of information from this website is entirely the responsibility of the user.