Chromium-dravite
A valid IMA mineral species
This page is currently not sponsored. Click here to sponsor this page.
About Chromium-dravite
Formula:
NaMg3Cr3+6(Si6O18)(BO3)3(OH)3(OH)
Colour:
Dark emerald-green to greenish-black.
Lustre:
Vitreous, Resinous
Hardness:
7 - 7½
Crystal System:
Trigonal
Member of:
Name:
For being the chromium analogue of dravite.
Tourmaline Group. The Cr3+ analogue of Dravite.
Originally named chromdravite (Rumantseva, 1983).
A detailed study by Vereshchagin et al. (2010) and Rozhdestvenskaya et al. (2011) strongly suggests that the "ideal" formula of chromdravite, NaMg3Cr6(BO3)3(Si6O18)(OH)4, is not realistic and should in fact be Na(Cr2Mg)(Cr4Mg2)(BO3)3(Si6O18)(OH)4 (Cr-Mg disorder on both Y and Z sites, leading to a more stable structure.)
Originally named chromdravite (Rumantseva, 1983).
A detailed study by Vereshchagin et al. (2010) and Rozhdestvenskaya et al. (2011) strongly suggests that the "ideal" formula of chromdravite, NaMg3Cr6(BO3)3(Si6O18)(OH)4, is not realistic and should in fact be Na(Cr2Mg)(Cr4Mg2)(BO3)3(Si6O18)(OH)4 (Cr-Mg disorder on both Y and Z sites, leading to a more stable structure.)
Unique Identifiers
Mindat ID:
1031
Long-form identifier:
mindat:1:1:1031:9
IMA Classification of Chromium-dravite
Approved
IMA status notes:
Published without approval
IMA Formula:
NaMg3Cr3+6(Si6O18)(BO3)3(OH)3OH
Approval history:
Published without approval: 2009
Classification of Chromium-dravite
9.CK.05
9 : SILICATES (Germanates)
C : Cyclosilicates
K : [Si6O18]12- 6-membered single rings, with insular complex anions
9 : SILICATES (Germanates)
C : Cyclosilicates
K : [Si6O18]12- 6-membered single rings, with insular complex anions
Dana 7th ed.:
61.3.1.13
61.3.1.11
61 : CYCLOSILICATES Six-Membered Rings
3 : Six-Membered Rings with borate groups
61 : CYCLOSILICATES Six-Membered Rings
3 : Six-Membered Rings with borate groups
17.5.37
17 : Silicates Containing other Anions
5 : Borosilicates
17 : Silicates Containing other Anions
5 : Borosilicates
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Cdrv | 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 Chromium-dravite
Vitreous, Resinous
Colour:
Dark emerald-green to greenish-black.
Streak:
Greyish-green.
Hardness:
7 - 7½ on Mohs scale
Optical Data of Chromium-dravite
Type:
Uniaxial (-)
RI values:
nω = 1.778 nε = 1.772
Max. Birefringence:
δ = 0.006
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Moderate
Chemistry of Chromium-dravite
Mindat Formula:
NaMg3Cr3+6(Si6O18)(BO3)3(OH)3(OH)
Element Weights:
Common Impurities:
Mn,Ti,V,Al,V,Ca
Crystallography of Chromium-dravite
Crystal System:
Trigonal
Class (H-M):
3m - Ditrigonal Pyramidal
Space Group:
R3m
Cell Parameters:
a = 16.11 Å, c = 7.27 Å
Ratio:
a:c = 1 : 0.451
Unit Cell V:
1,634.02 ų (Calculated from Unit Cell)
Z:
3
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 23 : Subaerial aqueous alteration by non-redox-sensitive fluids (see also #47) | |
| High-? alteration and/or metamorphism | |
| 31 : Thermally altered carbonate, phosphate, and iron formations |
Type Occurrence of Chromium-dravite
Synonyms of Chromium-dravite
Other Language Names for Chromium-dravite
German:Chromdravit
Russian:Хромдравит
Simplified Chinese:铬镁电气石
Spanish:Cromdravita
Traditional Chinese:鉻鎂電氣石
Relationship of Chromium-dravite to other Species
Member of:
Other Members of Tourmaline:
| Adachiite | CaFe3Al6(Si5AlO18)(BO3)3(OH)3(OH) | Trig. 3m : R3m |
| Alumino-oxy-rossmanite | ◻Al3Al6(Si5AlO18)(BO3)3(OH)3O | Trig. 3m : R3m |
| Bosiite | NaFe3+3(Al4Mg2)(Si6O18)(BO3)3(OH)3O | Trig. 3m : R3m |
| Celleriite | ◻(Mn2+2Al)Al6(Si6O18)(BO3)3(OH)3(OH) | Trig. 3m : R3m |
| Chromo-alumino-povondraite | NaCr3(Al4Mg2)(Si6O18)(BO3)3(OH)3O | Trig. 3m : R3m |
| Darrellhenryite | Na(Al2Li)Al6(Si6O18)(BO3)3(OH)3O | Trig. 3m : R3m |
| Dravite | NaMg3Al6(Si6O18)(BO3)3(OH)3(OH) | Trig. 3m : R3m |
| Dutrowite | Na(Fe2+2.5Ti0.5)Al6(Si6O18)(BO3)3(OH)3O | Trig. 3m : R3m |
| Elbaite | Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH) | Trig. 3m : R3m |
| Ertlite | NaAl3Al6(Si4B2O18)(BO3)3(OH)3O | Trig. 3m : R3m |
| Ferro-bosiite | NaFe3+3(Al4Fe2+2)(Si6O18)(BO3)3(OH)3O | Trig. 3m : R3m |
| Feruvite | CaFe2+3(Al5Mg)(Si6O18)(BO3)3(OH)3(OH) | Trig. 3m : R3m |
| Fluor-buergerite | NaFe3+3Al6(Si6O18)(BO3)3O3F | Trig. 3m : R3m |
| Fluor-dravite | NaMg3Al6(Si6O18)(BO3)3(OH)3F | Trig. 3m : R3m |
| Fluor-elbaite | Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3F | Trig. 3m : R3m |
| Fluor-liddicoatite | Ca(Li2Al)Al6(Si6O18)(BO3)3(OH)3F | Trig. 3m : R3m |
| Fluor-rossmanite | ◻(Al2Li)Al6(Si6O18)(BO3)3(OH)3F | Trig. 3m(32/m) : R3m |
| Fluor-schorl | NaFe2+3Al6(Si6O18)(BO3)3(OH)3F | Trig. 3m : R3m |
| Fluor-tsilaisite | NaMn2+3Al6(Si6O18)(BO3)3(OH)3F | Trig. 3m : R3m |
| Fluor-uvite | CaMg3(Al5Mg)(Si6O18)(BO3)3(OH)3F | Trig. 3m : R3m |
| Foitite | ◻(Fe2+2Al)Al6(Si6O18)(BO3)3(OH)3(OH) | Trig. 3m : R3m |
| Liddicoatite | Ca(Li2Al)Al6(Si6O18)(BO3)3(OH)3(OH) | Trig. 3m : R3m |
| Lucchesiite | CaFe2+3 Al6(Si6O18)(BO3)3(OH)3O | Trig. 3m : R3m |
| Magnesio-dutrowite | Na(Mg2.5Ti0.5)Al6(Si6O18)(BO3)3(OH)3O | Trig. 3m : R3m |
| Magnesio-foitite | ◻(Mg2Al)Al6(Si6O18)(BO3)3(OH)3(OH) | Trig. 3m : R3m |
| Magnesio-lucchesiite | CaMg3Al6(Si6O18)(BO3)3(OH)3O | Trig. 3m : R3m |
| Maruyamaite | K(Al2Mg)(Al5Mg)(Si6O18)(BO3)3(OH)3O | Trig. 3m : R3m |
| Olenite | NaAl3Al6(Si6O18)(BO3)3O3(OH) | Trig. 3m : R3m |
| Oxy-chromium-dravite | NaCr3(Cr4Mg2)(Si6O18)(BO3)3(OH)3O | Trig. 3m : R3m |
| Oxy-dravite | Na(Al2Mg)(Al5Mg)(Si6O18)(BO3)3(OH)3O | Trig. 3m : R3m |
| Oxy-foitite | ◻(Fe2+Al2)Al6(Si6O18)(BO3)3(OH)3O | Trig. 3m(32/m) : R3m |
| Oxy-schorl | Na(Fe2+2Al)Al6(Si6O18)(BO3)3(OH)3O | Trig. 3m : R3m |
| Oxy-vanadium-dravite | NaV3(V4Mg2)(Si6O18)(BO3)3(OH)3O | Trig. 3m : R3m |
| Povondraite | NaFe3+3(Mg2Fe3+4)(Si6O18)(BO3)3(OH)3O | Trig. 3m : R3m |
| Princivalleite | Na(Mn2Al)Al6(Si6O18)(BO3)3(OH)3O | Trig. 3m : R3m |
| Rossmanite | ◻(LiAl2)Al6(Si6O18)(BO3)3(OH)3(OH) | Trig. 3m : R3m |
| Schorl | NaFe2+3Al6(Si6O18)(BO3)3(OH)3(OH) | Trig. 3m : R3m |
| Tsilaisite | NaMn2+3Al6(Si6O18)(BO3)3(OH)3(OH) | Trig. 3m : R3m |
| 'UM2000-64-SiO:BFeHKMg' | (K,Na)Fe3+3(Mg2Fe3+4)Si6O18(BO3)3(OH)3O | |
| 'UM2008-52-SiO:AlBCaFFeHLiMgNa' | (Ca,Na,◻)(Al,Li,Fe,Mg)3Al6[Si6O18](BO3)3(OH,O)3(F,O) | |
| 'Unnamed (F analogue of feruvite)' | CaFe2+3(Al5Mg)(Si6O18)(BO3)3(OH)3F | |
| 'Unnamed (Mn2+-F-analogue of foitite)' | ◻(Mn2+2Al)Al6(Si6O18)(BO3)3(OH)3F ? | |
| 'Unnamed (Pb-analogue of Fluor-liddicoatite)' | Pb(Li2Al)Al6(Si6O18)(BO3)3(OH)3F | |
| Uvite | CaMg3(Al5Mg)(Si6O18)(BO3)3(OH)3(OH) | Trig. 3m : R3m |
| Vanadio-oxy-chromium-dravite | NaV3(Cr4Mg2)(Si6O18)(BO3)3(OH)3O | Trig. 3m : R3m |
| Vanadio-oxy-dravite | NaV3(Al4Mg2)(Si6O18)(BO3)3(OH)3O | Trig. 3m : R3m |
Common Associates
Related Minerals - Strunz-mindat Grouping
| 9.CK. | Adachiite | CaFe3Al6(Si5AlO18)(BO3)3(OH)3(OH) |
| 9.CK. | Magnesio-dutrowite | Na(Mg2.5Ti0.5)Al6(Si6O18)(BO3)3(OH)3O |
| 9.CK. | Darrellhenryite | Na(Al2Li)Al6(Si6O18)(BO3)3(OH)3O |
| 9.CK. | Fluor-schorl | NaFe2+3Al6(Si6O18)(BO3)3(OH)3F |
| 9.CK. | Princivalleite | Na(Mn2Al)Al6(Si6O18)(BO3)3(OH)3O |
| 9.CK. | Alumino-oxy-rossmanite | ◻Al3Al6(Si5AlO18)(BO3)3(OH)3O |
| 9.CK. | Dutrowite | Na(Fe2+2.5Ti0.5)Al6(Si6O18)(BO3)3(OH)3O |
| 9.CK. | Ferro-bosiite | NaFe3+3(Al4Fe2+2)(Si6O18)(BO3)3(OH)3O |
| 9.CK. | Bosiite | NaFe3+3(Al4Mg2)(Si6O18)(BO3)3(OH)3O |
| 9.CK. | Celleriite | ◻(Mn2+2Al)Al6(Si6O18)(BO3)3(OH)3(OH) |
| 9.CK.05 | Feruvite | CaFe2+3(Al5Mg)(Si6O18)(BO3)3(OH)3(OH) |
| 9.CK.05 | Fluor-rossmanite | ◻(Al2Li)Al6(Si6O18)(BO3)3(OH)3F |
| 9.CK.05 | Oxy-schorl | Na(Fe2+2Al)Al6(Si6O18)(BO3)3(OH)3O |
| 9.CK.05 | Fluor-elbaite | Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3F |
| 9.CK.05 | Dravite | NaMg3Al6(Si6O18)(BO3)3(OH)3(OH) |
| 9.CK.05 | Fluor-uvite | CaMg3(Al5Mg)(Si6O18)(BO3)3(OH)3F |
| 9.CK.05 | Foitite | ◻(Fe2+2Al)Al6(Si6O18)(BO3)3(OH)3(OH) |
| 9.CK.05 | Vanadio-oxy-dravite | NaV3(Al4Mg2)(Si6O18)(BO3)3(OH)3O |
| 9.CK.05 | Fluor-buergerite | NaFe3+3Al6(Si6O18)(BO3)3O3F |
| 9.CK.05 | 'Unnamed (F analogue of feruvite)' | CaFe2+3(Al5Mg)(Si6O18)(BO3)3(OH)3F |
| 9.CK.05 | Ertlite | NaAl3Al6(Si4B2O18)(BO3)3(OH)3O |
| 9.CK.05 | Tsilaisite | NaMn2+3Al6(Si6O18)(BO3)3(OH)3(OH) |
| 9.CK.05 | Fluor-liddicoatite | Ca(Li2Al)Al6(Si6O18)(BO3)3(OH)3F |
| 9.CK.05 | Uvite | CaMg3(Al5Mg)(Si6O18)(BO3)3(OH)3(OH) |
| 9.CK.05 | Elbaite | Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH) |
| 9.CK.05 | Fluor-tsilaisite | NaMn2+3Al6(Si6O18)(BO3)3(OH)3F |
| 9.CK.05 | Oxy-foitite | ◻(Fe2+Al2)Al6(Si6O18)(BO3)3(OH)3O |
| 9.CK.05 | Liddicoatite | Ca(Li2Al)Al6(Si6O18)(BO3)3(OH)3(OH) |
| 9.CK.05 | Vanadio-oxy-chromium-dravite | NaV3(Cr4Mg2)(Si6O18)(BO3)3(OH)3O |
| 9.CK.05 | Rossmanite | ◻(LiAl2)Al6(Si6O18)(BO3)3(OH)3(OH) |
| 9.CK.05 | Oxy-vanadium-dravite | NaV3(V4Mg2)(Si6O18)(BO3)3(OH)3O |
| 9.CK.05 | Olenite | NaAl3Al6(Si6O18)(BO3)3O3(OH) |
| 9.CK.05 | 'UM2000-64-SiO:BFeHKMg' | (K,Na)Fe3+3(Mg2Fe3+4)Si6O18(BO3)3(OH)3O |
| 9.CK.05 | Magnesio-lucchesiite | CaMg3Al6(Si6O18)(BO3)3(OH)3O |
| 9.CK.05 | Povondraite | NaFe3+3(Mg2Fe3+4)(Si6O18)(BO3)3(OH)3O |
| 9.CK.05 | Lucchesiite | CaFe2+3 Al6(Si6O18)(BO3)3(OH)3O |
| 9.CK.05 | Chromo-alumino-povondraite | NaCr3(Al4Mg2)(Si6O18)(BO3)3(OH)3O |
| 9.CK.05 | Fluor-dravite | NaMg3Al6(Si6O18)(BO3)3(OH)3F |
| 9.CK.05 | Oxy-dravite | Na(Al2Mg)(Al5Mg)(Si6O18)(BO3)3(OH)3O |
| 9.CK.05 | Oxy-chromium-dravite | NaCr3(Cr4Mg2)(Si6O18)(BO3)3(OH)3O |
| 9.CK.05 | 'Luinaite-(OH)' | NaFe2+3Al6(Si6O18)(BO3)3(OH)3(OH) |
| 9.CK.05 | Schorl | NaFe2+3Al6(Si6O18)(BO3)3(OH)3(OH) |
| 9.CK.05 | Magnesio-foitite | ◻(Mg2Al)Al6(Si6O18)(BO3)3(OH)3(OH) |
| 9.CK.05 | Maruyamaite | K(Al2Mg)(Al5Mg)(Si6O18)(BO3)3(OH)3O |
| 9.CK.10 | Abenakiite-(Ce) | Na26Ce6(Si6O18)(PO4)6(CO3)6(SO2)O |
| 9.CK.15 | Scawtite | Ca7(Si3O9)2CO3 · 2H2O |
| 9.CK.20 | Thorosteenstrupine | (Ca,Th,Mn)3Si4O11F · 6H2O |
| 9.CK.20 | Steenstrupine-(Ce) | Na14Mn2+2Fe3+2Ce6Zr(Si6O18)2(PO4)6(PO3OH)(OH)2 · 2H2O |
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 Chromium-dravite
mindat.org URL:
https://www.mindat.org/min-1031.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
External Links:
Mineral Dealers:
References for Chromium-dravite
Reference List:
Dunn, Pete J. (1977) Chromium in dravite. Mineralogical Magazine, 41 (319) 408-410 doi:10.1180/minmag.1977.041.319.21
Bosi, Ferdinando, Lucchesi, Sergio, Reznitskii, Leonid (2004) Crystal chemistry of the dravite-chromdravite series. European Journal of Mineralogy, 16 (2) 345-352 doi:10.1127/0935-1221/2004/0016-0345
Localities for Chromium-dravite
Showing 9 localities.
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.
Brazil | |
| erroneously reported [MinRec 33:209] |
Canada | |
| Alexandre et al. (2014) |
Finland | |
| ... |
India | |
| - (see explanation under chromoaluminopovondraite) |
Pakistan | |
| - (2002) |
Russia | |
| Pekov (1998) |
| Jeff Weissman collection (purchased from Excalibur Mineral Company) |
| Pekov (1998) |
USA | |
| Marian Lupulescu (New York State Museum) |
Quick NavTopAbout Chromium-draviteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Geological EnvironmentType Occurrence SynonymsOther LanguagesRelationshipsCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List


symbol to view information about a locality.
The
Srednyaya Padma mine, Zaonezhie peninsula, Medvezhyegorsky District, Republic of Karelia, Russia