Pyrochlore
| Pyrochlore Pyrochlore | |
|---|---|
 Pyrochlore from Uganda | |
| Classification | Oxide mineral |
| シュツルンツ classification | 04.DH.15 |
| Dana Classification | 08.02.01.01 Pyrochlore group |
| Chemical formula | (Na,Ca)2Nb2O6(OH,F) |
| Crystal system | Equiaxial crystal - Hexoctahedral |
| Symmetry | Equiaxial crystal 4/m 3 2/m |
| Unit cell | a = 10.41 (6)Å, Z=8 |
| Crystal habit | An octahedron is granular I lie scattered or grows up |
| Twin crystal | 111 (rare) |
| Pass, and come; open | 111 indistinctness, it is sometimes a cleavage |
| Fracture | Sub-shell form - heterogeneity is easy to be broken |
| 粘靱性 | Fragile |
| Mohs scale | 5.0–5.5 |
| Luster | Glass luster - resinous luster |
| Color | Black, brown, blackish brown, dark reddish-brown, umber, tango |
| Mark left on a bullet | White |
| Transparency | Semitransparency - opacity |
| Specific gravity | 4.45 - 4.90 |
| Optics characteristics | Isotropy, weak abnormality are anisotropic |
| Refractive index | n = 1.9–2.2 |
| Other characteristics | Radioactivity, メタミクト |
| Documents | [1][2][3] |
| A project: Mineral /Portal: Earth science | |
Pyrochlore (Pyrochlore) is composition-type (Na,Ca)2Nb2O6(OH,F), and, with a double oxide mineral of expressed sodium calcium niobium, niobium and tantalum become the solid solution in the ratio of an option. The thing of the master composes pyrochlore - microlite system of microlite pyrochlore, tantalum the thing of the master niobium.
Table of contents
Appearance
The pyrochlore is formed for last years of the replacement by the crackle of the magma. Own form crystals are seen in an octahedron of yellow - brown with resinous luster well, too, but are often made メタミクト because they include a radioactive element.
The pyrochlore is found in pegmatite and granite pegmatite, グライゼン of alkaline rocks such as the nepheline syenite. I do a collection of body in the car VONA tight inside and may form a niobium deposit. For a coexistence mineral with zircon, aegirine, apatite, perovskite, the columbite [1].
Discovery and naming
In 1826, a specimen of スタヴェルン (フレドリクスヴェルン) of Norwegian ヴェストフォル prefecture ラルヴィク was listed. Because I changed color in green when I ran for blowpipe analysis, it was named pyrochlore by χλωρός(chlores) which meant πΰρ(pyro) and green to mean fire or heat in Greek [2].
Crystal structure
The crystal structure of the pyrochlore is called "pyrochlore structure" (Fd-3m) in a cubic system generally. More generally, A2B2O6 and A2B2O7 mean the structure of the expressed material (e.g., Y2Ti2O7) when I assumed A, B a rare-earth element or a transition metal element together. With a superstructure body consisting of the fluorite structure (AO2 = A4O8) that the pyrochlore structure is simple, positive ion A and B are aspect direction <110> に went and lined up. In addition, an anion can be in the gap of a certain tetrahedron form between the positive ions of the adjacent B site. This is the lattice system which is inherent in geometric frustration and brings about a specific magnetic effect.
The material of the pyrochlore structure shows insulator (La2Zr2O7), ionic conductive material (Gd1.9Ca0.1Ti2O6.9), metallic conductive material (Bi2Ru2O7-y), spin ice magnetic body (Dy2Ti2O7), spin glass magnetic body (Y2Mo2O7), Hull den chain (one-dimensional antiferromagnetic chain) (Tl2Ru2O7), a variety of physical properties including superconductor (Cd2Re2O7).
Niobium mine
Each three major production centers of the niobium ore is a pyrochlore deposit. The maximum thing is CBMM mine of the Minas Gerais アラシャ south of Brazil, and it is カタラン mine in the east of Goias カタラン to be next to it. It is ニオベック mine in the western part of town サントノーレ in the suburbs of Canada Quebec シクーティミ to be the third biggest [4].
The pyrochlore includes more than 0.05% of uranium and thorium and often has radioactivity [5].
Footnote
- It is rruff.info. ^ a b "pyrochlore at RRuff database" February 3, 2015 reading.
- It is mindat.org. ^ a b "Pyrochlore Group: Pyrochlore Group mineral information and data." February 3, 2015 reading.
- ^ Barthelmy, Dave. It is webmineral.com. "Pyrochlore Mineral Data" February 3, 2015 reading.
- ^ J. Kouptsidis, F. Peters, D. Proch, W. Singer. "Niob für TESLA". September 2, 2008 reading.
- ^ Dias da Cunha, K.; M. Santos, F. Zouain1, L. Carneiro1, G. Pitassi, C. Lima, C. V. Barros Leite and K. C. P. Dália (May 8, 2009). "Dissolution Factors of Ta, Th, and U Oxides Present in Pyrochlore." Water, Air, & Soil Pollution (Springer Netherlands) 205 (1-4): 251–257. doi: 10.1007/s11270-009-0071-3. ISSN 0049-6979.
References
- "Oxide Pyrochlores - A Review", M.A. Subramanian, G. Aravamudan and G. V. Subba Rao, Progress in Solid State Chemistry, Volume 15 (1983) pp. 55-143
- Atencio, D., Andrade, M. B., Christy, A. G., Gieré, R., & Kartashov, P. M. (2010). The pyrochlore supergroup of minerals: nomenclature. The Canadian Mineralogist, 48(3), 673-698.doi: 10.3749/canmin.48.3.673
Allied item
This article is taken from the Japanese Wikipedia Pyrochlore
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