Theophrastite
A valid IMA mineral species
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About Theophrastite
Theophrastus
Formula:
Ni(OH)2
Colour:
Emerald Green
Lustre:
Silky
Hardness:
3½
Specific Gravity:
4.00
Crystal System:
Trigonal
Member of:
Name:
Named after Theophrastus (ca 371-286 BCE), Greek philosopher and writer, disciple of Aristotle. Although commonly known by his honorary name, his given name was Tyrtamus. Author in about 315 BCE of Περι λιθων, "On Stones" possibly the first mineralogy book.
Type Locality:
Unique Identifiers
Mindat ID:
3936
Long-form identifier:
mindat:1:1:3936:5
IMA Classification of Theophrastite
Classification of Theophrastite
4.FE.05
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
E : Hydroxides with OH, without H2O; sheets of edge-sharing octahedra
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
E : Hydroxides with OH, without H2O; sheets of edge-sharing octahedra
6.2.1.5
6 : HYDROXIDES AND OXIDES CONTAINING HYDROXYL
2 : X(OH)2
6 : HYDROXIDES AND OXIDES CONTAINING HYDROXYL
2 : X(OH)2
7.22.3
7 : Oxides and Hydroxides
22 : Oxides of Ni
7 : Oxides and Hydroxides
22 : Oxides of Ni
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 |
|---|---|---|
| Tph | 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 Theophrastite
Silky
Transparency:
Translucent
Colour:
Emerald Green
Streak:
Light green
Hardness:
3½ on Mohs scale
Cleavage:
Perfect
on {0001}
on {0001}
Fracture:
Conchoidal
Density:
4.00 g/cm3 (Measured) 3.95 g/cm3 (Calculated)
Optical Data of Theophrastite
Type:
Uniaxial (+)
RI values:
nω = 1.759 - 1.760 nε = 1.759 - 1.760
Birefringence:
Very weak
Surface Relief:
Very High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized uniaxial interference figure - the conoscopic
(convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis
centred and vertical. The coloured rings are isochromatics, computed with the
same physics as the Michel-Lévy bar above; the dark cross is the isogyre.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
Pleochroism:
Weak
Chemistry of Theophrastite
Mindat Formula:
Ni(OH)2
Elements listed:
Crystallography of Theophrastite
Crystal System:
Trigonal
Class (H-M):
3m(32/m) - Hexagonal Scalenohedral
Space Group:
P3m1
Cell Parameters:
a = 3.131 Å, c = 4.608 Å
Ratio:
a:c = 1 : 1.472
Unit Cell V:
39.12 ų (Calculated from Unit Cell)
Z:
1
Morphology:
Platy, fibrous, botyroidal crusts.
Comment:
On synthetic
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
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Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Display Options
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
View
CIF File Best | x | y | z | a | b | c
CIF File Best | x | y | z | a | b | c
Rotation
Stop | Start
Stop | Start
Labels
Console Off | On | Grey | Yellow
Console Off | On | Grey | Yellow
Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0009939 | Theophrastite | Ramesh T N, Kamath P V, Shivakumara C (2006) Classification of stacking faults and their stepwise elemination during the disorder -> order transformation of nickel hydroxide Acta Crystallographica B62 530-536 |  | 2006 | synthetic | 0 | 293 |
| 0011791 | Theophrastite | Wyckoff R W G (1963) Second edition. Interscience Publishers, New York, New York Crystal Structures 1 239-444 | 1963 | 0 | 293 | ||
| 0018023 | Theophrastite | Cairns R, Ott E (1933) X-ray studies of the system nickel-oxygen-water. I. Nickelous oxide and hydroxide _cod_database_code 1011134 Journal of the American Chemical Society 55 527-533 | 1933 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.335 Å | (100) |
| 4.61 Å | (95) |
| 1.755 Å | (50) |
| 2.708 Å | (30) |
| 1.563 Å | (25) |
| 1.480 Å | (18) |
| 1.336 Å | (10) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 3a: Earth’s earliest Hadean crust | >4.50 |
| 7 : Ultramafic igneous rocks | |
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] |
Geological Setting:
Chromatites
Type Occurrence of Theophrastite
General Appearance of Type Material:
Small crystals of "0.n" [sic] mm but usually forms thin layers , thickness less than 0.5 cm. In some cases forms successive layers consisting of very fine fibrous crystals aligned perpendicular to the boundaries of vesuvianite or chlorite crystals.
Place of Conservation of Type Material:
National Museum of Natural History, Washington, D.C., USA, 148460.
Geological Setting of Type Material:
In cavities and fractures of magnetite-chromite ore in serpentinite.
Associated Minerals at Type Locality:
Synonyms of Theophrastite
Other Language Names for Theophrastite
Relationship of Theophrastite to other Species
Member of:
Other Members of Brucite Group:
| Amakinite | Fe2+(OH)2 | Trig. |
| Brucite | Mg(OH)2 | Trig. 3m(32/m) : P3m1 |
| Portlandite | Ca(OH)2 | Trig. 3m(32/m) : P3m1 |
| Pyrochroite | Mn(OH)2 | Trig. 3m(32/m) : P3m1 |
Related Minerals - Strunz-mindat Grouping
| 4.FE. | Nannoniite | Al2(OH)5F |
| 4.FE.05 | Brucite | Mg(OH)2 |
| 4.FE.05 | Amakinite | Fe2+(OH)2 |
| 4.FE.05 | Portlandite | Ca(OH)2 |
| 4.FE.05 | Pyrochroite | Mn(OH)2 |
| 4.FE.10 | Doyleite | Al(OH)3 |
| 4.FE.10 | Bayerite | Al(OH)3 |
| 4.FE.10 | Nordstrandite | Al(OH)3 |
| 4.FE.10 | Gibbsite | Al(OH)3 |
| 4.FE.15 | Lepidocrocite | Fe3+O(OH) |
| 4.FE.15 | Böhmite | AlO(OH) |
| 4.FE.20 | Heterogenite | Co3+O(OH) |
| 4.FE.20 | Grimaldiite | CrO(OH) |
| 4.FE.25 | Lithiophorite | (Al,Li)MnO2(OH)2 |
| 4.FE.25 | Feitknechtite | Mn3+O(OH) |
| 4.FE.30 | Quenselite | PbMnO2(OH) |
| 4.FE.35 | Ferrihydrite | Fe3+10O14(OH)2 |
| 4.FE.40 | Vernadite | (Mn4+,Fe3+,Ca,Na)(O,OH)2 · nH2O |
| 4.FE.40 | Feroxyhyte | Fe3+O(OH) |
| 4.FE.45 | Quetzalcoatlite | Zn6Cu3(TeO6)2(OH)6 · AgxPbyClx+2y |
| 4.FE.50 | Fuettererite | Pb3Cu2+6Te6+O6(OH)7Cl5 |
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 Theophrastite
mindat.org URL:
https://www.mindat.org/min-3936.html
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Please feel free to link to this page.
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References for Theophrastite
Reference List:
Marcopoulos, Theodor, Economou, Maria (1981) Theophrastite, Ni(OH)2, a new mineral from northern Greece. American Mineralogist, 66 (9-10) 1020-1021
Livingstone, A., Bish, D. L. (1982) On the new mineral theophrastite, a nickel hydroxide, from Unst, Shetland, Scotland. Mineralogical Magazine, 46 (338) 1-5 doi:10.1180/minmag.1982.046.338.01
Localities for Theophrastite
Showing 7 localities.
symbol to view information about a locality.
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.
Australia | |
| Henry et al. (1992) +1 other reference |
Canada | |
| Horváth et al. (2013) |
Greece (TL) | |
| Marcopoulos et al. (1981) +1 other reference |
Italy | |
| Bedognè et al. (1993) |
Japan | |
| Arai +4 other references |
Russia | |
| Pavel M. Kartashov analytical data (2013) |
UK | |
| Bish et al. (1981) +2 other references |
Quick NavTopAbout TheophrastiteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesRelationshipsStrunz-MindatOther InformationInternet Links References Localities Locality List
Vermio, Central Macedonia, Greece