Zinc Gartrellite
| Zinc Gartrellite | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 1998-014 |
| chemical formula |
|
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.CG.20 ( 8th edition : VII / C.31) 02.33.02.02 |
| Similar minerals | Gartrellit |
| Crystallographic Data | |
| Crystal system | triclinic |
| Crystal class ; symbol | triclinic pinacoidal; 1 |
| Space group | P 1 (No. 2) |
| Lattice parameters |
a = 5.550 Å ; b = 5.620 Å; c = 7.621 Å, α = 68.59 °; β = 69.17 °; γ = 69.51 ° |
| Formula units | Z = 1 |
| Frequent crystal faces | {111} |
| Physical Properties | |
| Mohs hardness | 4.5 |
| Density (g / cm 3 ) | 5.30 (calculated) |
| Cleavage | no |
| Break ; Tenacity | not determined; brittle |
| colour | greenish yellow, light yellow |
| Line color | yellow |
| transparency | translucent to translucent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.91 n β = 1.94 (calculated) n γ = 1.97 |
| Birefringence | δ = 0.06 |
| Optical character | biaxial negative |
| Axis angle | 2V = 87 ° (measured) |
| Pleochroism | weak from X = Z = pale yellow to Y = yellow |
| Other properties | |
| Chemical behavior | Completely soluble in warm dilute HCl |
Zinc gartrellite is a very rarely occurring mineral from the mineral class of " phosphates , arsenates and vanadates ". It crystallizes in the triclinic crystal system with the chemical composition Pb (Zn, Fe 3+ , Cu) 2 (AsO 4 ) 2 (H 2 O, OH) 2 and is therefore chemically seen a hydrous lead - zinc - iron - copper - arsenate with a variable proportion of additional hydroxide ions .
Zinc gartrellite develops aggregates up to 0.5 mm in size, which are made up of very small, yellow-green, {111} tabular crystals up to 0.1 mm in size. The type locality of the mineral is the Tsumeb Mine in Namibia, where it appeared on massive chalcosine together with wulfenite , fragranceite and fragrance-β (intermediate mixed crystal between fragranceite and konichalcite) as well as konichalcite , cuproadamine and olivite .
Etymology and history
Gerd Tremmel (* 1940), who acquired the mineral in Tsumeb in the late 1970s, is considered the discoverer of zinc gartrellite . As a result, the type level can be assigned to the mining period between 1975 and 1980.
Initial investigations led to the result that it is a previously unknown type of mineral, which was presented in 1998 as "zincian gartrellite". After further mineralogical, chemical and structural work, the mineral was recognized in 1998 by the International Mineralogical Association (IMA) under the number "IMA 1998-014" and in 2000 by an Austrian-German research team with Herta Silvia Effenberger , Werner Krause , Heinz- Jürgen Bernhardt and Mirko Martin described in the English science magazine "Mineralogical Magazine" as zinc gartrellite.
The mineral was named because of the dominance of zinc on the Me (2) positions and the close chemical and structural relationship with its copper-dominant and zinc-free analogue Gartrellite . Gartrellit sensu stricto was named after the Australian collector Blair Gartrell (1950–1995).
Type material of the mineral (holotype) is stored in the Institute for Mineralogy, Geology and Geophysics of the Ruhr University Bochum in Germany (catalog no. 081).
classification
The current classification of the International Mineralogical Association (IMA) counts zinc gartrellite to the tsumcorite group with the general formula Me (1) Me (2) 2 (XO 4 ) 2 (OH, H 2 O) 2 , in which Me (1), Me (2) and X different positions in the structure of the minerals of the tsumcorite group with Me (1) = Pb 2+ , Ca 2+ , Na + , K + and Bi 3+ ; Me (2) = Fe 3+ , Mn 3+ , Cu 2+ , Zn 2+ , Co 2+ , Ni 2+ , Mg 2+ and Al 3+ and X = As 5+ , P 5+ , V 5+ and represent S 6+ . To Tsumcoritgruppe include not only Zinkgartrellit still Cabalzarit , Cobaltlotharmeyerit , Cobalttsumcorit , Ferrilotharmeyerit , Gartrellit , Helmutwinklerit , Kaliochalcit , Krettnichit , Lotharmeyerit , Lukrahnit , Manganlotharmeyerit , Mawbyit , Mounanait , Natrochalcit , Nickellotharmeyerit , Nickelschneebergit , Nickeltsumcorit , Phosphogartrellit , Rappoldit , Schneebergit , Thometzekit , Tsumcorit and Yancowinnait .
In the meantime outdated, but still in use 8th edition of the mineral classification by Strunz of Zinkgartrellit belonged to the mineral class of "phosphates, arsenates and vanadates" and then to the Department of "water containing phosphates without foreign anions " where he along with Cabalzarit , Cobaltlotharmeyerit , Cobalttsumcorit , Ferrilotharmeyerit , Gartrellit , Helmutwinklerit , Krettnichit , Lotharmeyerit , Lukrahnit , Manganlotharmeyerit , Mawbyit , Mounanait , Nickellotharmeyerit , Nickelschneebergit , Phosphogartrellit , Rappoldit , Schneebergit , Thometzekit and Tsumcorit the "Tsumcorit-Gartrellit group" with the system number. VII / C.31 formed.
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 zinc gartrellite 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 phosphate, arsenate or vanadate complex to the water of crystallization content , so that the mineral can be classified according to its composition in the subsection “With large and medium-sized cations; RO 4 : H 2 O = 1: 1 "is to be found, where together with the other members gartrellite , helmutwinklerite , lukrahnite , phosphogartrellite and rappoldite the" Helmutwinklerite group "with the system no. 8.CG.20 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns zinc gartrellite to the class of "phosphates, arsenates and vanadates" and there in the department of "composite phosphates etc.". Here it is together with Gartrellit and Lukrahnit in the " Gartrellite Group " with the system no. 43.02.02 within the subsection " Compound phosphates etc., (water-containing, normally composed anions)".
Chemism
Sixteen microprobe analyzes on zinc gartrellite resulted in mean values of 33.49% PbO; 0.35% CaO; 7.23% Fe 2 O 3 ; 0.26% Al 2 O 3 ; 11.40% ZnO; 6.26% CuO; <0.5% CoO, <0.5% NiO, 34.72% As 2 O 5 ; 0.13% SO 3 and 4.3% H 2 O (theoretical content). From this, the empirical formula (Pb 0.96 Ca 0.04 ) Σ = 1.00 (Zn 0.89 Cu 0.50 Fe 3+ 0.58 Al 0.03 ) Σ = 2 was calculated on the basis of 10 oxygen atoms , 00 [(AsO 4 ) 1.99 (SO 4 ) 0.01 ] Σ = 2.00 [(OH) 0.61 (H 2 O) 1.39 ] Σ = 2.00 , corresponding to Pb (Zn , Fe, Cu) 2 (AsO 4 ) 2 (H 2 O, OH) 2 .
Zinc gartrellite is a representative of the tsumcorite group . The general formula for the tsumcorite group is Me (1) Me (2) 2 (XO 4 ) 2 (OH, H 2 O) 2 with Me (1) = Pb, Ca, Na and Bi; Me (2) = Fe, Mn, Cu, Zn, Co, Ni and Al as well as X = P, As, V and S. Mixed crystal formation occurs mainly on the Me (2) position, but less frequently on the X and Me positions (1) position instead. Zinc gartrellite and gartrellite form a mixed crystal series with the following structural formula: Pb (Zn x Fe 3+ 1 − x ) (Zn x Cu 1 − x ) (AsO 4 ) 2 (OH) 1 − x (H 2 O) 1 + x . In zinc gartrellite , x: 0.4 <x <-0.8 applies. Crystals with 0 <x <0.4 can be assigned to gartrellite , while crystals with x ≈ 1.0 correspond to helmutwinklerite , which differs from zinc gartrellite through certain structural features.
Due to the need for a charge equalization for the different cations Me (1) 1 +, 2 +, 3 + and Me (2) 2 +, 3 + as well as X 4 +, 6 + , considerable amounts of H 2 O are created in the zinc gartrellite by hydroxyl groups ( (OH) - ) substituted.
Zinc gartrellite is chemically closely related to helmutwinklerite and is the zinc-dominant analogue of the copper-dominated gartrellite.
Crystal structure
Zinc gartrellite crystallizes in the triclinic crystal system in the space group P 1 (space group no. 2) with the lattice parameters a = 5.550 Å ; b = 5.620 Å; c = 7.621 Å; α = 68.59 °; β = 69.17 ° and γ = 69.51 ° as well as one formula unit per unit cell .
The crystal structure of zinc gartrellite consists of coordination polyhedra , which are linked by common edges to form chains parallel [010]. AsO 4 - tetrahedra with common corners connect these chains, creating layers lying parallel to the ab surface. The layers are connected by hydrogen bonds and by Pb [6 + 2] atoms at the Me (1) position, which occupy specific positions with symmetry 1 between these layers. The Me (2) position is split as in the other representatives of the triclinic Tsumcoritgruppe in two different positions. As in the gartrellite, the triclinic symmetry of the zinc gartrellite is caused by the different stereochemical requirements of iron and copper. The splitting of the Me (2) position into two positions, Me (2a) and Me (2b), allows the assumption of different crystal-chemical environments: for Me (2a) [6] O 6 the octahedral coordination, which is caused by the Fe 3 + Atoms is retained. The coordination polyhedron Me (2b) [4 + 2] O 6 , on the other hand, is distorted because the Cu 2+ atoms prefer the tetragonal-bipyramidal [4 + 2] coordination due to their electron configuration caused by the Jahn – Teller effect . Zinc atoms can substitute both Fe 3+ and Cu and are consequently also found in both the Me (2a) and the Me (2b) positions.
The minerals of the tsumcorite group can be divided into three different subgroups (tsumcorite, helmutwinklerite and gartrellite subgroup), which are characterized by different structural types. Zinc gartrellite is one of the representatives of the gartrellite subgroup, which is characterized by the orderly occupation of the Me (2) position by cations with different crystal chemical behavior (here: Fe 3+ and Cu 2+ ). Considerable differences in the Zn contents are observed in the gartrellite-zinc gartrellite mixed crystal series. Chemical and structural data consistently show that Zn substitutes for Fe and Cu in almost equal amounts. The size of the triclinic distortion is controlled by the (Fe, Cu): Zn ratio. In the pure Zn end link, the Me (2) O 6 polyhedron is an octahedron . In this case the structure type changes to that of the Helmutwinklerite subgroup.
Zinc gartrellite is isotypic (isostructural) to gartrellite, but not to helmutwinklerite.
properties
morphology
According to {111}, zinc gartrellite forms tabular crystals up to 0.1 mm in size, which come together to form rosette-shaped aggregates up to 0.5 mm in size. The crystals are usually poorly developed and have grown together intensively. The form that determines the costume is the pinacoid in general position {111}, the crystal costume is completed by the pinacoids {100}, {110} and {010}. Other crystals are tabular developed according to { 1 11}. Here { 1 11} is the form that determines the costume, the pinacoids {111}, {110} and {001} appear as terminating surface forms.
On the type stage, the zinc gartrellite sits on massive chalcosine and covers an area of approx. 4 cm². It was also found in the form of crusts made of tiny tabular crystals <0.1 mm in size.
physical and chemical properties
The crystals of the zinc gartrellite are greenish yellow to light yellow, its line color is indicated as yellow. The surfaces of the translucent to transparent crystals have a glass-like sheen , which is also in accordance with the values for the refraction of light (n x = 1.91, n z = 1.97).
The mineral shows no cleavage , the type of fracture form of the brittle zinc gartrellite could not be determined due to the poor formation of its crystals. With a Mohs hardness of 4.5, zinc gartrellite is one of the medium-hard minerals, so it stands between the reference minerals fluorite (hardness 4) and apatite (hardness 5) and can be easily scratched with a pocket knife like these more (fluorite) or less (apatite). The density of the mineral could not be measured, its calculated density is 5.30 g / cm³.
Zinc gartrellite is completely soluble in warm dilute hydrochloric acid (HCl).
Education and Locations
Zinc gartrellite is a typical secondary mineral and arises in the oxidation zone of arsenic-containing hydrothermal lead-zinc deposits . In the Tsumeb Mine it was formed from sulphides containing lead, zinc and copper, such as galena , sphalerite and chalcosine, the arsenic originating from the decomposition of the arsenic ore tennantite .
Accompanying minerals from the original find in the Tsumeb Mine are chalcosine as well as wulfenite, fragranceite, konichalcite, intermediate fragranceite-konichalcite mixed crystals, cuproadamine and oliveite. It also appeared, together with zinc olivenite and quartz, on silicified (silicified), mineralized dolomite stone .
As a very rare mineral formation, zinc gartrellite could only be described by its type locality so far (as of 2017) . As a type locality which is considered world-famous, in dolomite stones fitting, hydrothermal , poly- Cu-Pb-Zn-Ag-Ge-Cd deposit of "Tsumeb Mine" (Tsumcorp Mine) in Tsumeb region Oshikoto , Namibia , the exact Fund point for the material is unknown from the type publication.
Zinc Gartrellite in Germany , Austria and Switzerland are therefore unknown.
use
Due to its rarity, zinc gartrellite is only of interest to mineral collectors.
See also
literature
- Herta Effenberger, Werner Krause, Heinz-Jürgen Bernhardt, Mirko Martin: On the symmetry of tsumcorite grou p minerals based on the new species rappoldite and zincgartrellite . In: Mineralogical Magazine . 64 (Issue 6), 2000, pp. 1109–1126 , doi : 10.1180 / 002646100549922 ( rruff.info [PDF; 1.1 MB ]).
Web links
- Mineral Atlas: Zinc Gartrellite (Wiki)
- Mindat - Zinc Gartrellite (English)
- Mineralogical Association of Canada - Zinc Gartrellite (English)
- Webmineral - Zinc Gartrellite (English)
- American-Mineralogist-Crystal-Structure-Database - Zinc Gartrellite (English)
Individual evidence
- ↑ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae Herta Effenberger, Werner Krause, Heinz-Jürgen Bernhardt, Mirko Martin: On the symmetry of tsumcorite group minerals based on the new species rappoldite and zincgartrellite . In: Mineralogical Magazine . 64 (Issue 6), 2000, pp. 1109–1126 , doi : 10.1180 / 002646100549922 ( rruff.info [PDF; 1.1 MB ]).
- ^ 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. 730 .
- ↑ Mindat - Zinc Gartrellite
- ↑ Kharisun, Max R. Taylor, DJM Bevan, Allan Pring: The crystal chemistry of duftite, PbCuAsO4 (OH) and the β-duftite problem . In: Mineralogical Magazine . tape 62 , 1998, pp. 121–130 , doi : 10.1180 / 002646198547413 ( rruff.info [PDF; 269 kB ]).
- ↑ a b c d Werner Krause, Klaus Belendorff, Heinz-Jürgen Bernhardt, Catherine McCammon, Herta Effenberger, Werner Mikenda: Crystal chemistry of the tsumcorite-group minerals. New data on ferrilotharmeyerite, tsumcorite, thometzekite, mounanaite, helmutwinklerite, and a redefinition of gartrellite . In: European Journal of Mineralogy . tape 10 , 1998, pp. 179-206 , doi : 10.1127 / ejm / 10/2/0179 .
- ^ A b Ernest H. Nickel , BW Robinson, O. Fitz Gerald, William D. Birch: Gartrellite, a new secondary arsenate mineral from Ashburton Downs, WA and Broken Hill, NSW In: Australian Mineralogist . tape 4 , 1989, pp. 83-89 .
- ^ Type mineral catalog Germany - storage of the holotype stage zinc gartrellite
- ↑ Catalog of Type Mineral Specimens - Z. (PDF 30 kB) In: docs.wixstatic.com. Commission on Museums (IMA), December 12, 2018, accessed August 29, 2019 .
- ↑ a b Mineralienatlas - Zinkgartrellite
- ↑ a b c www.tsumeb.com - Zinc Gartrellite
- ↑ Mindat - Number of localities for zinc gartrellite
- ↑ Find location list for zinc gartrellite in the Mineralienatlas and Mindat