Mathhewrogersite
| Mathhewrogersite | |
|---|---|
| General and classification | |
| other names |
IMA 1984-042 |
| chemical formula |
|
|
Mineral class (and possibly department) |
Silicates and germanates, ring silicates (cyclosilicates) |
|
System no. to Strunz and to Dana |
9.JA.15 ( 8th edition : VIII / E.02) 78.03.01.01 |
| Crystallographic Data | |
| Crystal system | trigonal |
| Crystal class ; symbol | trigonal-pyramidal; 3 , trigonal rhombohedral; 3 , trigonal trapezoidal; 32 , ditrigonal pyramidal; 3 m or ditrigonal-scalenohedral; 3 2 / m , |
| Space group | R 3 (No. 146) , R 3 (No. 148) , R 32 (No. 155) , R 3 m (No. 160) or R 3 m (No. 166) |
| Lattice parameters | a = 8.457 Å ; c = 45.970 Å |
| Formula units | Z = 3 |
| Physical Properties | |
| Mohs hardness | ≈ 2 |
| Density (g / cm 3 ) | 4.7 (measured); 4.76 (calculated) |
| Cleavage | very perfect after {0001} |
| Break ; Tenacity | not specified; not specified |
| colour | colorless, white to pale greenish yellow |
| Line color | White |
| transparency | transparent |
| shine | Glass luster, weak mother-of-pearl luster on cleavage surfaces |
| Crystal optics | |
| Refractive indices |
n ω = 1.810 n ε = 1.745 |
| Refractive index | n = 1.788 (measured); 1.771 (calculated) |
| Birefringence | δ = 0.065 |
| Optical character | uniaxial negative |
| Other properties | |
| Chemical behavior | soluble in ENT 3 |
Mathewrogersite is a very rarely occurring mineral from the mineral class of " silicates and germanates " (formerly oxides and hydroxides ). It crystallizes in the trigonal crystal system with the chemical formula Pb 7 (Fe, Cu) GeAl 3 Si 12 O 36 (OH, H 2 O, □) 6 , so chemically speaking it is a lead - iron - germanium - aluminum silicate with additional hydroxide ions . Structurally, mathrogersite belongs to the ring silicates ( cyclosilicates ).
Mathewrogersite forms idiomorphic, according to {0001} thin-plate crystals up to a maximum of 0.3 mm in size or hemispherical to spherical groups of intergrown lamellar and scaly aggregates , which show a radial structure and reach sizes of approx. 1 mm. The mineral was found together with queitite , alamosite , melanotekite , kegelite , larsenite , schaurteit , anglesite , willemite , leadhillite and mimetesite in the Tsumeb Mine , Namibia.
Etymology and history
The Australian mineralogist John Innes (? –1992), chief mineralogist of the Tsumeb Corporation in the late 1970s, who noticed the mineral among other specimens from Tsumeb, is considered to be the discoverer of the Mathhewrogersite . Corresponding investigations led to the determination of the presence of a new mineral, which was recognized in 1984 by the International Mineralogical Association (IMA) under the number "IMA 1984-042" and in 1986 by a German-American research team with Paul Keller from the University of Stuttgart and Pete J. Dunn of the Smithsonian Institution was described as mathrogersite in the science magazine "New Yearbook for Mineralogy, Monthly Books".
The mineral was named after Mathew Rogers, the first prospector in Tsumeb. Rogers played an important role in finding the “Green Hill” from which the “Tsumeb Mine” developed. With the granting of a concession for more than 50,000 km² for the mining of mineral raw materials in Damaraland and Otavibergland to South West Afrika Corp. on September 12, 1892, the requirement was to send an expedition to the concession area immediately. This expedition, led by the mining engineer Mathew Rogers, arrived in the Otavibergland in 1893. Rogers first examined the occurrences of "Gross Otavi" and "Klein Otavi" (Kombat). However, he soon learned of other deposits that were secretly mined by the natives and tried to locate them. On January 12, 1893, Rogers stood in front of the ore outcrop of Tsumeb called "Tsautsomb" by the locals. Its description in an enthusiastic letter to the management of the South West Africa Corp. in London on January 21, 1893 is the first written report on Tsumeb, one of the most legendary deposits in the world. Parts of this letter are printed in Gerhard Söhnge's monograph on Tsumeb.
"I have been holding places of trust for the past 24 years, have visited various countries of the world, inspecting mines, mineral outcrops, and prospecting for minerals; have been associated with the minerals gold, silver, tin, copper and lead; but in the whole of my experience, I have never seen such a sight as was presented before my view at Soomep, and I very much doubt if I shall ever see such another in any other locality. "
Type material of the mineral is in the archives of the University of Stuttgart in the "Mineralogical Collection of Professor Keller" (register no. TM-84.42-TL-8904.01 at location 0/824-s27 / 2, holotype) and in the National belonging to the Smithsonian Institution Museum of Natural History , Washington, DC (Cotyp).
classification
Already in the outdated but still partially in use 8th edition of the mineral classification by Strunz of Mathewrogersit belonged to the mineral class of "silicates and Germanates" and then to the Department of "Ring silicates", where he together with Margarosanit , Roeblingit and Walstromit with the "Walstromitgruppe" the system no. VIII / E.02 .
The 9th edition of Strunz's mineral systematics, which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns the mathrogersite to the class of "silicates and germanates", but there it is in the "germanates" class. Here he can be found as the only member of the unnamed group 9.JA.15 within the previously unnamed subdivision “A”.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , also assigns the mathrogersite to the class of "silicates and Germanates", but there in the department of "unclassified silicate minerals". Here he is the only member of the unnamed group 78.03.01 within the subdivision of " Unclassified Silicates: Possible Ring Silicates ".
Chemism
A microprobe analysis on mathrogersite showed 57.5% PbO; 1.7% FeO; 3.9% GeO 2 ; 0.8% CuO; 5.9% Al 2 O 3 ; 0.1% MgO; 26.2% SiO 2 and 1.9% H 2 O. On the basis of 12 silicon atoms per formula unit, the empirical formula Pb 7.08 (Fe 0.65 Cu 0.28 Mg 0.07 ) Σ = 1 was calculated , 00 Al 3.18 Ge 1.03 Si 12 O 41.81 H 5.81 , which was idealized to Pb 7 (Fe, Cu) GeAl 3 Si 12 O 36 (OH, H 2 O, □) 6 . The composition of Pb 7 (Fe 0.67 Cu 0.33 ) GeAl 3 Si 12 O 36 (OH) 5 , which roughly corresponds to the latter formula, requires 58.73% PbO; 1.89% FeO; 3.92% GeO 2 ; 0.9% CuO; 5.75% Al 2 O 3 ; 27.10% SiO 2 and 1.70% H 2 O.
Crystal structure
Mathewrogersit crystallized trigonal in the space group R 3 (space group no. 146) , R 3 (no. 148) , R 32 (no. 155) , R 3 m (no. 160) , or R 3 m (no. 166) with the lattice parameters a = 8.457 Å and c = 45.970 Å and three formula units per unit cell .
The structure of the mathrogersite is still unknown and there are no structural relationships to other minerals or chemical substances.
properties
morphology
On the two finds with mathrogersite known at the time of the first description, the mineral is formed differently and associated with different secondary minerals. Mathewrogersite is found in subparallel fused idiomorphic, thin-plate to tabular crystals based on the pinacoid {0001} base with a maximum diameter of 0.3 mm and a hexagonal cross-section. They have a six-sided outline made up of tiny, non-indexable surfaces, which could be rhombohedral surfaces . In addition, mathrogersite forms scaly to stalky grains, which can come together to form radial hemispherical to spherical aggregates with a maximum diameter of 1 mm.
physical and chemical properties
Math rogerite crystals are colorless or white to pale greenish-yellow, their streak color , however, is always white. The surfaces of the water-clear, transparent crystals show a clear glass-like sheen , with a faint pearlescent sheen on the cracked surfaces. Mathewrogersite has a high light refraction and a very high birefringence (δ = 0.065).
The crystals of the mathrogersite show a very perfect cleavage according to {0001}. The mineral has a Mohs hardness of ≈ 2 and is one of the soft minerals that can be scratched with a fingernail , similar to the reference mineral gypsum . The measured density of the mathrogersite is ≈ 4.7 g / cm³, the calculated density is 4.76 g / cm³.
Mathewrogersite is well soluble in hot nitric acid HNO 3 .
Education and Locations
Mathewrogersite occurs as a typical secondary formation in heavily corroded lead-zinc ores in the oxidation zone of a complex Cu-Pb-Zn deposit in carbonate rocks. Lead, iron and germanium originate from the decomposition of primary Germanium - ores and sulfidic ore minerals as Germanit , Renierit and galena .
The mathrogersite crystals are grown on a matrix of hematite , chalcosine and quartz . No obvious relationship with Mathewrogersit the following, also secondary education representative to come on the same level Begleitminerale before: typical white, pearlescent rosettes Kegelit scales, and white Schaurteit needles, small, also tabular, white or water clear Leadhillit crystals and brown until 1 cm large, idiomorphic angelsite crystals. On the other find, the mathrogersite aggregates are closely intergrown with other oxide lead minerals. Older than Mathewrogersit are Leadhillit, alamosite and Queitit is the same age, Melanotekit . Mathewrogersite and Melanotekit occur in two generations and grew up directly on Alamosite or Queitite. The youngest minerals are willemite , larsenite and mimetesite .
As a very rare mineral formation, Mathewrogersite could only be described from one source so far (as of 2016). Its type locality is the world-famous Cu-Pb-Zn-Ag-Ge-Cd deposit of the "Tsumeb Mine" (Tsumcorp Mine) in Tsumeb , Oshikoto Region , Namibia . The exact location within the "Tsumeb Mine" is the 31st level in the E9 pillar.
use
Due to its rarity, mathrogersite is only of interest to mineral collectors.
See also
literature
- Paul Keller, Pete J. Dunn: Mathewrogersite, a new lead silicate mineral from Tsumeb, Namibia . In: New yearbook for mineralogy, monthly books . 1986 (issue 5), 1986, p. 203-208 .
- Mathewrogersit , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF, 66 kB )
Web links
- Mineral Atlas: Mathewrogersite (Wiki)
- Webmineral - Mathewrogersite (English)
- Mindat - Mathewrogersit (English)
Individual evidence
- ↑ a b c d e f g h i j k l m n o p q Paul Keller, Pete J. Dunn: Mathewrogersite, a new lead silicate mineral from Tsumeb, Namibia . In: New yearbook for mineralogy, monthly books . 1986 (issue 5), 1986, p. 203-208 .
- ^ A b Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 609 .
- ↑ a b Mathewrogersit , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF, 66 kB )
- ↑ a b Georg Gebhard: Tsumeb . 1st edition. GG Publishing, Grossenseifen 1999, p. 276 + 322 .
- ↑ Paul Keller: Tsumeb / Namibia - one of the most spectacular mineral discovery sites on earth . In: Lapis . 9 (issue 7/8), 1984, p. 13-63 .
- ^ Gerhard Söhnge: Tsumeb: a historical scetch (Scientific research in South West Africa (5th series)) . 1st edition. Publisher of the SWA Scientific Society, Windhoek 1967, p. 18 .
- ↑ Type mineral catalog Germany - storage of the holotype stage Mathewrogersit
- ↑ Catalog of Type Mineral Specimens - M. (PDF 124 kB) In: docs.wixstatic.com. Commission on Museums (IMA), December 12, 2018, accessed August 29, 2019 .
- ↑ Mindat - Number of localities for Mathewrogersite
- ↑ Find location list for Mathewrogersite at the Mineralienatlas and at Mindat