Reddingit
| Reddingit | |
|---|---|
 |
|
| General and classification | |
| chemical formula |
|
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.CC.05 ( 8th edition : VII / C.08) 03/40/02/03 |
| Crystallographic Data | |
| Crystal system | orthorhombic |
| Crystal class ; symbol | orthorhombic-dipyramidal; 2 / m 2 / m 2 / m |
| Room group (no.) | Pbna (No. 60) |
| Lattice parameters | a = 9.49 Å ; b = 10.08 Å; c = 8.70 Å |
| Formula units | Z = 4 |
| Frequent crystal faces | {111}, {212}, {221}, {010}, {223}, {122} |
| Physical Properties | |
| Mohs hardness | 3 to 3.5 |
| Density (g / cm 3 ) | measured: 3.10 to 3.24; calculated: 3.26 |
| Cleavage | indistinct after {010} |
| Break ; Tenacity | uneven; brittle |
| colour | light pink to brownish yellow, colorless |
| Line color | White |
| transparency | transparent to translucent |
| shine | Glass gloss, resin gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.643 to 1.658 n β = 1.648 to 1.664 n γ = 1.674 to 1.685 |
| Birefringence | δ = 0.031 |
| Optical character | biaxial positive |
| Axis angle | 2V = measured: 41 to 65 °; calculated: 48 to 58 ° |
| Pleochroism | visible: X = colorless; Y = brownish pink; Z = light yellow |
Reddingite is a rarely occurring mineral from the mineral class of "phosphates, arsenates and vanadates". It crystallizes in the orthorhombic crystal system with the idealized chemical composition Mn 2+ 3 (PO 4 ) 2 · 3H 2 O and is thus a water-containing manganese - phosphate .
Reddingite is the manganese analogue of phosphoferrite (Fe 2+ 3 (PO 4 ) 2 · 3H 2 O) and forms a complete mixed crystal row with it . The formula for Reddingit is therefore also given as (Mn, Fe 2+ ) 3 [PO 4 ] 2 · 3H 2 O in various sources . The elements indicated in the round brackets can represent each other in the formula ( substitution , diadochie), but are always in the same proportion to the other components of the mineral.
The mineral usually develops tabular or pseudo- octahedral crystals , but also occurs in the form of granular to massive mineral aggregates . The transparent to translucent crystals are light pink to brownish-yellow in color and have a glass-like to resin-like sheen on the surface . Reddingites that are colorless or appear white due to multiple refraction due to lattice construction defects or polycrystalline formation are seldom found. The line color of the mineral is also white.
With a Mohs hardness of 3 to 3.5, Reddingite is one of the medium-hard minerals that, like the reference minerals calcite (Mohs hardness 3) and fluorite (4), can be scratched with a copper coin or easily with a pocket knife .
Etymology and history
Reddingite was first discovered in the Branchville quarry near the city of Redding in Fairfield County , Connecticut . The mineral was first described in 1878 together with eosphorite by George Jarvis Brush and Edward Salisbury Dana , who named it after its type locality (Redding).
The type material is held at Yale University in New Haven, Connecticut (Catalog Nos. 3.5850, 3.5851).
classification
Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the reddingite belonged to the mineral class of "phosphates, arsenates and vanadates" and there to the department of "water-containing phosphates without foreign anions ", where together with garyansellite , kryzhanovskit and Phosphoferrite the "Phosphoferrite series" with the system no. VII / C.08 .
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 reddingite to the category of “phosphates etc. without additional anions; with H 2 O “. However, this is further subdivided according to the relative size of the cations involved and the molar ratio of the phosphate, arsenate or vanadate complex to the water of crystallization contained , so that the mineral is classified in the sub-section “With only medium-sized cations; RO 4 : H 2 O = 1: 1.5 "is to be found, where together with garyansellite, kryzhanovskite, landesite and phosphoferrite the" phosphoferrite group "with the system no. 8.CC.05 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Reddingite to the class of "phosphates, arsenates and vanadates" and there in the department of "water-containing phosphates etc.". Here he is also in the " phosphoferrite group " with system no. 40.03.02 within the sub-section "Water-containing phosphates etc., with (A 2+ ) 3 (XO 4 ) 2 × x (H 2 O)".
Education and Locations
Reddingite forms as a hydrothermal conversion product from lithiophilite and is mostly found in granitic pegmatites . In addition to lithiophilite, other accompanying minerals can include dickinsonite , eosphorite , fairfieldite , hureaulite , rhodochrosite , triplite and triploidite .
As a rare mineral formation, Reddingite could only be detected at a few sites, with around 30 sites known so far (as of 2014). In addition to its Branchville / Redding type locality, the mineral was also found in the United States (USA) in the Strickland quarry near Collins Hill in Middlesex County in Connecticut, as well as in various locations in the states of Maine , New Hampshire and South Dakota .
In Germany, reddingite has so far only been found near Plößberg , near Hopfau (municipality of Kemnath ) and near Hagendorf (Markt Waidhaus ) in the Upper Palatinate Forest in Bavaria.
Other previously known sites include the Ranquel pegmatites in the Argentine department of Coronel Pringles , several locations in the Docetal ( Doce valley ) of the Brazilian state of Minas Gerais , the Viitaniemi pegmatites in the vicinity of the former municipality of Eräjärvi (today Orivesi ) in Finland, the phosphate-rich granite pegmatites at Yukiiri near the city of Kasumigaura on the Japanese island of Honshū and Bendada (Guarda), Meixedo (Viana do Castelo) and Regada near the city of Mangualde (Viseu) in Portugal.
Crystal structure
Reddingite crystallizes orthorhombically in the space group Pbna (space group no. 60) with the lattice parameters a = 9.49 Å ; b = 10.08 Å and c = 8.70 Å and 4 formula units per unit cell .
See also
literature
- GJ Brush, ES Dana: On a new and remarkable mineral locality in Fairfield County, Connecticut; with a description of several new species occurring there. First paper. In: American Journal of Science and Arts. Volume 116, 1878, pp. 33-46; 114–123 ( rruff.info PDF; 1.21 MB).
- GJ Brush, ES Dana, HL Wells: On the mineral locality at Branchville, Connecticut: Fifth paper. In: American Journal of Science. Volume 134, 1890, pp. 201-216 ( rruff.info PDF; 2.61 MB).
- Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1987, ISBN 3-342-00288-3 , p. 640 .
Web links
Individual evidence
- ↑ a b c IMA / CNMNC List of Mineral Names; July 2014 (PDF; 1.5 MB).
- ↑ a b c d e 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. 477 .
- ↑ Webmineral - Reddingite.
- ↑ a b c d Reddingite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( handbookofmineralogy.org PDF; 66 , 2 kB).
- ↑ a b c d Mindat - Reddingite.
- ↑ Mindat - picture example of a colorless, pseudo-octahedral reddingite crystal.
- ^ Friedrich Klockmann : Klockmanns textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 640 (first edition: 1891).
- ↑ Mindat - Number of locations for Reddingit.
- ↑ List of locations for Reddingit in the Mineralienatlas and Mindat .