Iridescent coating
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About Iridescent coating
Not really a true mineral, but a nanomineral: a nanoscale coating on another mineral (frequently iron oxides or hydroxides, but not exclusively). It is commonly only a few hundred nanometers thick, so extremely difficult to analyse and characterise by normal mineralogical techniques.
These iridescent specimens are commonly found on hematite and/or goethite, and often given the name turgite for this reason by collectors. One research report suggests an aluminium phosphate (or less commonly aluminium arsenate) coating (Chi Ma and George R. Rossman, unpublished paper submitted to Am Min.: http://minerals.gps.caltech.edu/manuscripts/in-prep/submitted/rainbow_hematite/) . A more recent study found these iridescent hematite coatings are composed of aggregates of nano-rods of hematite containing Al and P impurities (Lin et al., 2018).
This page is a placeholder mostly for photos that were incorrectly classed as "turgite" and they should generally be moved to more appropriate positions if analysed correctly (the underlying material, not the coating): usually either hematite or goethite.
These iridescent specimens are commonly found on hematite and/or goethite, and often given the name turgite for this reason by collectors. One research report suggests an aluminium phosphate (or less commonly aluminium arsenate) coating (Chi Ma and George R. Rossman, unpublished paper submitted to Am Min.: http://minerals.gps.caltech.edu/manuscripts/in-prep/submitted/rainbow_hematite/) . A more recent study found these iridescent hematite coatings are composed of aggregates of nano-rods of hematite containing Al and P impurities (Lin et al., 2018).
This page is a placeholder mostly for photos that were incorrectly classed as "turgite" and they should generally be moved to more appropriate positions if analysed correctly (the underlying material, not the coating): usually either hematite or goethite.
Unique Identifiers
Mindat ID:
55263
Long-form identifier:
mindat:1:1:55263:3
Common Associates
Associations Based on Photo Data:
| 45 photos of Iridescent coating associated with Quartz | SiO2 |
| 32 photos of Iridescent coating associated with Hematite | Fe2O3 |
| 24 photos of Iridescent coating associated with Goethite | Fe3+O(OH) |
| 10 photos of Iridescent coating associated with Calcite | CaCO3 |
| 9 photos of Iridescent coating associated with Rutile | TiO2 |
| 6 photos of Iridescent coating associated with Kyanite | Al2(SiO4)O |
| 4 photos of Iridescent coating associated with Jarosite | KFe3+3(SO4)2(OH)6 |
| 4 photos of Iridescent coating associated with 'Limonite' | |
| 3 photos of Iridescent coating associated with Magnetite | Fe2+Fe3+2O4 |
| 2 photos of Iridescent coating associated with Smithsonite | ZnCO3 |
Other Information
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 Iridescent coating
mindat.org URL:
https://www.mindat.org/min-55263.html
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References for Iridescent coating
Localities for Iridescent coating
Showing 15 localities.
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The Locality List
- 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).
All localities listed without proper references should be considered as questionable.
Chile | |
| observed at the University of Atacama ... +1 other reference |
USA | |
| Luetcke (n.d.) |
| Luetcke (n.d.) |
| Luetcke (n.d.) |
| Luetcke (n.d.) |
| Luetcke (n.d.) |
| Luetcke (n.d.) |
| Luetcke (n.d.) | |
| Luetcke (n.d.) |
| Rolf Luetcke |
| Rolf Luetcke |
| Luetcke (n.d.) |
| Luetcke (n.d.) |
| Luetcke (n.d.) +1 other reference |
| Luetcke (n.d.) |
Nakhon Si Thammarat Province, Thailand