Picromerite (original) (raw)
A valid IMA mineral species - grandfathered
About PicromeriteHide
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Formula:
K2Mg(SO4)2 · 6H2O
Colour:
Colourless, white, reddish, yellowish, grayish; colourless in transmitted light.
Crystal System:
Monoclinic
Name:
From the Greek for "bitter" and "part" in allusion to the presence of magnesium and was originally applied to material crystallized from an aqueous solution of mixed salts from Vesuvius fumaroles.
Picromerite Group.
Fresh picromerite is colorless. Specimens may dehydrate in collections within days to years (according to the conditions) to white, opaque leonite.
Picromerite-type compounds are labeled Tutton salts in chemistry.
Unique IdentifiersHide
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Long-form identifier:
mindat:1:1:3206:9
6cbe7f45-a421-45ee-863f-38f440f2bb8f
IMA Classification of PicromeriteHide
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Approved, 'Grandfathered' (first described prior to 1959)
Type description reference:
Classification of PicromeriteHide
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7.CC.60
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
C : Sulfates (selenates, etc.) without additional anions, with H2O
C : With medium-sized and large cations
29.3.6.1
29 : HYDRATED ACID AND NORMAL SULFATES
3 : A2B(XO4)2·xH2O
25.3.15
25 : Sulphates
3 : Sulphates of Mg
Mineral SymbolsHide
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As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference |
|---|---|---|
| Pmr | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of PicromeriteHide
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Colour:
Colourless, white, reddish, yellowish, grayish; colourless in transmitted light.
Comment:
Tints due to admixed materials
Cleavage:
Perfect
On {201}, perfect.
Density:
2.028 g/cm3 (Measured) 2.031 g/cm3 (Calculated)
Comment:
Measured on artificial material.
Optical Data of PicromeriteHide
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RI values:
_n_α = 1.461 _n_β = 1.463 _n_γ = 1.476
2V:
Measured: 48° , Calculated: 46°
δ = 0.015
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Chemistry of PicromeriteHide
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Mindat Formula:
K2Mg(SO4)2 · 6H2O
Crystallography of PicromeriteHide
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Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Cell Parameters:
a = 9.066 Å, b = 12.254 Å, c = 6.128 Å
β = 104.78°
Ratio:
a:b:c = 0.74 : 1 : 0.5
Unit Cell V:
658.26 ų (Calculated from Unit Cell)
Morphology:
Short prismatic [001]. Crusts on other salts; also massive.
Crystal StructureHide
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X-Ray Powder DiffractionHide
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Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 4.16 Å | (85) |
| 4.06 Å | (95) |
| 3.71 Å | (100) |
| 3.16 Å | (40) |
| 3.06 Å | (70) |
| 2.964 Å | (60) |
| 2.813 Å | (40) |
Comments:
Powder data from synthetic material.
Geological EnvironmentHide
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Geological Setting:
In kainite zones of some oceanic salt deposits.
Type Occurrence of PicromeriteHide
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Place of Conservation of Type Material:
No designated type material.
Geological Setting of Type Material:
Active volcanic fumaroles.
Reference:
Guarini, G., Palmieri, L., Scacchi, A. (1855) Chapter 5. Esame mineralogico-chimico delle produzioni dell'incendio. in Memoria sullo Incendio Vesuviano, Gaetano Nobile (Napoli): 165-200 (191).
Synonyms of PicromeriteHide
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Other Language Names for PicromeriteHide
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Simplified Chinese:软钾镁矾
Traditional Chinese:軟鉀鎂礬
Relationship of Picromerite to other SpeciesHide
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Other Members of this group:
Common AssociatesHide
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Associated Minerals Based on Photo Data:
Related Minerals - Strunz-mindat GroupingHide
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Other InformationHide
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Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for PicromeriteHide
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References for PicromeriteHide
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Reference List:
Bosi, F., Belardi, G., Ballirano, P. (2009) Structural features in Tutton's salts K2M2+(H2O)62, with M2+ = Mg, Fe, Co, Ni, Cu, and Zn. American Mineralogist, 94 (1) 74-82 doi:10.2138/am.2009.2898
Localities for PicromeriteHide
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This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the 
symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
Locality ListHide
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- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for references and further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. 
- Good crystals or important locality for species. 
- World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).
All localities listed without proper references should be considered as questionable.