Hidalgoite
| Hidalgoite | ||
|---|---|---|
Specific gravity 3.71–3.96 | | |
| Optical properties | Uniaxial (+) | |
| Refractive index | nω = 1.713–1.730 nε = 1.715–1.735 | |
| References | [2][3][4] | |
Hidalgoite, PbAl3(AsO4)(SO4)(OH)4, is a rare member of the
Hidalgoite is categorized under the
Composition
Hidalgoite was collected from a quartz vein at the Zimapán mining area after which it was examined by Smith in the laboratories.
Structure
The structure of Hidalgoite is a complex structure consisting of a monovalent cation, a tri valent cation and two almost equal anion groups. The hidalgoite structure is different from other members of the beaudantite in that, in the other beaudantite group minerals, the oxygen and the hydroxyl bind to the sulfate group along the chain whereas, in hidalgoite, the hydroxyl and oxygen bond to the sulfate group but the hydrogen is also bonded with the arsenate anion.[6] The hidalgoite structure has cation preference on all three sites, Pb being the preferred monovalent site, Fe for the trivalent cation site, and arsenic and phosphate for the anion site. The structure shows no ordering between the arsenate group and the phosphate group.[7] According to the alunite family structure, a super group of hidalgoite is made up of octahedral layers that touch at the corners, on top and bottom of the octahedral layers are tetrahedra that connect to one another by sharing three of their apices with the octahedra. The unbounded apex areas are usually bonded to by oxygen atoms or hydroxyl atoms and the layers are held together by the lead cations.[8] The hydrogen atoms bond to the corners of the octahedral that are not being occupied.[8]
Physical properties
Hidalgoite is usually seen as light gray to dark gray colors but other variety of colors are seen to include rich shades of green, some dark reds and very rarely yellow. Hidalgoite minerals are characterized with a white streak and possess a dull and earthy luster. Beaudantite group members show good cleavage on {001}. Hidalgoite specimens have irregular fractures and due to its brittle nature breaks conchoidally. The hardness of the mineral is 4.5 and the density ranges from 3.96g/cm3 to 4.5g/cm3 due to impurities from associated minerals.[5]
Geologic occurrence
The occurrences of hidalgoite have been seen across many continents from South America to Africa. It was initially discovered between large bodies of quartz dike as a white porous substance alongside other sulfates but has since been seen in other parts of the world. In Nye County, Nevada, hidalgoite is seen as clear prismatic crystals with other secondary lead minerals such as mimetite and beaudantite. In certain parts of Australia, hidalgoite is found between distorted sedimentary layers of shale and greywack, it is mostly found in uplifted layers of rocks. A special type of hidalgoite called phillipsbornite-hidalgoite was discovered at Tsumeb, Namibia as bladed yellow-green masses dotted with azurite crystals in large quartz matrix. In Broken Hill, Australia, hidalgoite minerals are found in large quantities according to unidentified sources, this could be as a result of contamination of groundwater with oxygen which causes the sulfide ores to dissolve and recrystallize forming new secondary minerals. Other places where hidalgoite can be seen are Spain, France and England.
References
- S2CID 235729616.
- ^ Hidalgoite in the Handbook of Mineralogy
- ^ Hidalgoite on Mindat.org
- ^ Hidalgoite data on Webmineral
- ^ a b c d e f Smith et al. 1953 Smith, Robert, S. Frank Simons, and C. Angelina Vlisidis, Hidalgoite, a New Mineral, American Mineralogist, 1953, pp. 1218–1224
- ISSN 0022-2860.
- ^ Szymanski, Jan (1988). "The Crystal Structure of Beudantite, Pb(Fe, Al)3[(As, S)O4]2(OH)6" (PDF). Canadian Mineralogist. 26: 923–932.
- ^ S2CID 131400736.
- Anthony, John W., and Sidney Arthur Williams. “Mineralogy of Arizona.” Tucson : University of Arizona Press, 1977. Print.
- Castor, Stephen B., Ferdock C. Gregory. “Minerals of Nevada.” Reno: Nevada Bureau of Mines and Geology in association with University of Nevada Press, 2004. Print.
- Rattray, K. J.; Taylor, M. R.; Bevan, D. J. M.; Pring, A. (1996). "Compositional Segregation and Solid Solution in the Lead-Dominant Alunite-Type Minerals from Broken Hill, N.S.W.". Mineralogical Magazine. 60 (402): 779–785. S2CID 54821564.
- "Hidalgoite: Hidalgoite mineral information and data". Mindat.org. Retrieved 19 December 2013.
- Simons, Frank S., and Eduardo, Mapes V., “Geology and ore deposits of the Zimápán mining district, State of Hidalgo, Mexico”,. Washington: U.S. Govt. Print. Off., 1956. Print.