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Greenalite
A valid IMA mineral species - grandfathered
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About Greenalite
Formula:
(Fe2+,Fe3+)2-3Si2O5(OH)4
Colour:
green, light yellow-green
Lustre:
Dull, Earthy
Hardness:
2½
Specific Gravity:
2.85 - 3.15
Crystal System:
Monoclinic
Member of:
Name:
Named in allusion to its green colour.
Type Locality:
Unique Identifiers
Mindat ID:
1745
Long-form identifier:
mindat:1:1:1745:5
Similar Names
| Granulite | A rock classification type |
IMA Classification of Greenalite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
(Fe2+,Fe3+)2-3Si2O5(OH)4
Classification of Greenalite
9.ED.15
9 : SILICATES (Germanates)
E : Phyllosilicates
D : Phyllosilicates with kaolinite layers composed of tetrahedral and octahedral nets
9 : SILICATES (Germanates)
E : Phyllosilicates
D : Phyllosilicates with kaolinite layers composed of tetrahedral and octahedral nets
71.1.2b.4
71 : PHYLLOSILICATES Sheets of Six-Membered Rings
1 : Sheets of 6-membered rings with 1:1 layers
71 : PHYLLOSILICATES Sheets of Six-Membered Rings
1 : Sheets of 6-membered rings with 1:1 layers
14.19.6
14 : Silicates not Containing Aluminum
19 : Silicates of Fe
14 : Silicates not Containing Aluminum
19 : Silicates of Fe
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Gre | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Gre | Siivolam & Schmid (2007) | Siivolam, J. and Schmid, R. (2007) Recommendations by the IUGS Subcommission on the Systematics of Metamorphic Rocks: List of mineral abbreviations. Web-version 01.02.07. IUGS Commission on the Systematics in Petrology. download |
| Gre | Whitney & Evans (2010) | Whitney, D.L. and Evans, B.W. (2010) Abbreviations for names of rock-forming minerals. American Mineralogist, 95, 185–187 doi:10.2138/am.2010.3371 |
| Gre | The Canadian Mineralogist (2019) | The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download |
| Gre | Warr (2020) | Warr, L.N. (2020) Recommended abbreviations for the names of clay minerals and associated phases. Clay Minerals, 55, 261–264 doi:10.1180/clm.2020.30 |
Physical Properties of Greenalite
Dull, Earthy
Transparency:
Translucent
Colour:
Green, light yellow-green
Streak:
Greenish-gray
Hardness:
2½ on Mohs scale
Density:
2.85 - 3.15 g/cm3 (Measured)
Optical Data of Greenalite
Type:
Biaxial (+)
RI values:
nα = 1.65 - 1.675 nβ = 1.674 nγ = 1.674
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 biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
No measured or calculated 2V is on file for this mineral, so the value used here (180°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
No measured or calculated 2V is on file for this mineral, so the value used here (180°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
Dispersion:
weak
Pleochroism:
Visible
Comments:
Pale yellow to green
Comments:
Isotropic when fine grained. n = 1.670
Chemistry of Greenalite
Mindat Formula:
(Fe2+,Fe3+)2-3Si2O5(OH)4
Element Weights:
Elements listed:
Common Impurities:
Al,Mn,Mg
Crystallography of Greenalite
Polytype:
Formula:
Crystal System:
Class (H-M)
Space Group:
Space Group Setting:
Cell Parameters:
Ratio:
Unit Cell Volume (calc):
Z:
Comment:
| Greenalite-1A | Greenalite-1M | Greenalite-2Å | Greenalite-2M1 | Greenalite-3Å | Greenalite-3R |
|---|---|---|---|---|---|
| (Fe2+,Fe3+)2-3Si2O5(OH)4 | (Fe2+,Fe3+)2-3Si2O5(OH)4 | (Fe2+,Fe3+)2-3Si2O5(OH)4 | (Fe2+,Fe3+)2-3Si2O5(OH)4 | (Fe2+,Fe3+)2-3Si2O5(OH)4 | (Fe2+,Fe3+)2-3Si2O5(OH)4 |
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) |
|---|---|---|---|---|---|---|---|
| 0000136 | Greenalite | Shirozu H, Bailey S W (1965) Chlorite polytypism: III. Crystal structure of an orthohexagonal iron chlorite American Mineralogist 50 868-885 |  | 1965 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 7.12 Å | (80) |
| 3.559 Å | (80) |
| 2.849 Å | (20) |
| 2.571 Å | (100) |
| 2.184 Å | (40) |
| 1.593 Å | (60) |
| 1.553 Å | (40) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 2: Planetesimal differentiation and alteration | 4.566-4.550 |
| 6 : Secondary asteroid phases | 4.566-4.560 |
| Near-surface Processes | |
| 21 : Chemically precipitated carbonate, phosphate, iron formations | |
| High-𝑇 alteration and/or metamorphism | |
| 32 : Ba/Mn/Pb/Zn deposits, including metamorphic deposits |
Type Occurrence of Greenalite
Place of Conservation of Type Material:
National Museum of Natural History, Washington, D.C., USA, 91160, 124953.
Geological Setting of Type Material:
banded iron formation
Associated Minerals at Type Locality:
Other Language Names for Greenalite
Relationship of Greenalite to other Species
Member of:
Other Members of Kaolinite-Serpentine Group:
| Kaolinite Subgroup | Al2Si2O5(OH)4 | |
| Manandonite | Li2Al4(Si2AlB)O10(OH)8 | Orth. 222 : C2221 |
| Odinite | (Fe,Mg,Al,Fe,Ti,Mn)2.4((Si,Al)2O5)(OH)4 | Mon. m : Bm |
| Serpentine Subgroup | D3[Si2O5](OH)4 |
Forms a series with:
Dalnegorsk, Dalnegorsk Urban District, Primorsky Krai, Russia