Rankinite
A valid IMA mineral species - grandfathered
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About Rankinite
Formula:
Ca3Si2O7
Colour:
Colourless
Lustre:
Vitreous
Hardness:
5½
Specific Gravity:
2.96 - 3.00
Crystal System:
Monoclinic
Name:
Named in honor of George Atwater Rankin (7 October 1884 - 21 March 1963), physical chemist at the Geophysical Laboratory, Washington, D.C., USA. He studied the CaO-SiO2 and CaO-Al2O3-SiO2 system and first found the compound.
Type Locality:
This page provides mineralogical data about Rankinite.
Unique Identifiers
Mindat ID:
3363
Long-form identifier:
mindat:1:1:3363:9
IMA Classification of Rankinite
Approved, 'Grandfathered' (first described prior to 1959)
First published:
1942
Classification of Rankinite
9.BC.15
9 : SILICATES (Germanates)
B : Sorosilicates
C : Si2O7 groups, without non-tetrahedral anions; cations in octahedral [6] and greater coordination
9 : SILICATES (Germanates)
B : Sorosilicates
C : Si2O7 groups, without non-tetrahedral anions; cations in octahedral [6] and greater coordination
55.3.1.1
55 : SOROSILICATES Si2O7 Groups,Generally with no Additional Anions
3 : Si2O7 Groups, Generally with no Additional Anions with cations in [7] coordination
55 : SOROSILICATES Si2O7 Groups,Generally with no Additional Anions
3 : Si2O7 Groups, Generally with no Additional Anions with cations in [7] coordination
14.5.4
14 : Silicates not Containing Aluminum
5 : Silicates of Ca
14 : Silicates not Containing Aluminum
5 : Silicates of Ca
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 |
|---|---|---|
| Rnk | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Rnk | 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 |
| Rnk | The Canadian Mineralogist (2019) | The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download |
Physical Properties of Rankinite
Vitreous
Transparency:
Transparent, Translucent
Colour:
Colourless
Hardness:
5½ on Mohs scale
Cleavage:
Perfect
(100)
(100)
Density:
2.96 - 3.00 g/cm3 (Measured) 3.00 g/cm3 (Calculated)
Optical Data of Rankinite
Type:
Biaxial (+)
RI values:
nα = 1.640 - 1.643 nβ = 1.643 - 1.646 nγ = 1.650 - 1.652
2V:
Measured: 62° to 69°, Calculated: 72° to 80°
Max. Birefringence:
δ = 0.009 - 0.010
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
Dispersion:
relatively weak r > v
Comments:
Y = b; X^a = 15 deg
Chemistry of Rankinite
Mindat Formula:
Ca3Si2O7
Element Weights:
Elements listed:
Crystallography of Rankinite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/b
Setting:
P21/a
Cell Parameters:
a = 10.557(1) Å, b = 8.885(3) Å, c = 7.858(1) Å
β = 119.586(6)°
β = 119.586(6)°
Ratio:
a:b:c = 1.188 : 1 : 0.884
Unit Cell V:
640.97 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Rarely as prismatic crystals, to 8 mm
Crystal Structure
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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) |
|---|---|---|---|---|---|---|---|
| 0014417 | Rankinite | Saburi S, Kusachi I, Henmi C, Kawahara A, Henmi K, Kawada I (1976) Refinement of the structure of rankinite Mineralogical Journal 8 240-246 |  | 1976 | 0 | 293 | |
| 0014416 | Rankinite | Kusachi I, Henmi C, Kawahara A, Henmi K (1975) The structure of rankinite Mineralogical Journal 8 38-47 | | 1975 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.717 Å | (100) |
| 3.18 Å | (80) |
| 4.48 Å | (70) |
| 3.84 Å | (70) |
| 3.03 Å | (60) |
| 1.819 Å | (60) |
| 3.20 Å | (50) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-? alteration and/or metamorphism | |
| 31 : Thermally altered carbonate, phosphate, and iron formations | |
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 51 : Pyrometamorphic minerals (see also #54 and #56) | <0.36 |
Geological Setting:
High temperature contact metamorphism of impure limestones.
Type Occurrence of Rankinite
General Appearance of Type Material:
rounded or irregular grains.
Place of Conservation of Type Material:
The Natural History Museum, London, England, 1956,386.
Geological Setting of Type Material:
High temperature metamorphism at contact between limestone and flint.
Associated Minerals at Type Locality:
Other Language Names for Rankinite
Common Associates
Associations Based on Photo Data:
| 3 photos of Rankinite associated with Wollastonite | Ca3(Si3O9) |
| 3 photos of Rankinite associated with 'Andradite-Schorlomite Series' | |
| 3 photos of Rankinite associated with Gehlenite | Ca2Al[AlSiO7] |
| 2 photos of Rankinite associated with Kilchoanite | Ca6(SiO4)(Si3O10) |
| 2 photos of Rankinite associated with Aradite | BaCa6[(SiO4)(VO4)](VO4)2F |
| 2 photos of Rankinite associated with Melilite Group | Ca2M(XSiO7) |
| 1 photo of Rankinite associated with Magnetite | Fe2+Fe3+2O4 |
| 1 photo of Rankinite associated with Perovskite | CaTiO3 |
| 1 photo of Rankinite associated with Schorlomite | Ca3Ti2(SiO4)(Fe3+O4)2 |
| 1 photo of Rankinite associated with Wollastonite Group |
Related Minerals - Strunz-mindat Grouping
| 9.BC. | Anorthoyttrialite-(Y) | Y4(SiO4)(Si3O10) |
| 9.BC. | Kozłowskiite | Ca4(Fe2+Sn3)[Si2O7]2[Si2O6OH]2 |
| 9.BC.05 | Yttrialite-(Y) | (Y,Th)2Si2O7 |
| 9.BC.05 | Thortveitite | Sc2Si2O7 |
| 9.BC.05 | Keiviite-(Y) | Y2Si2O7 |
| 9.BC.05 | Keiviite-(Yb) | Yb2Si2O7 |
| 9.BC.05 | Gittinsite | CaZrSi2O7 |
| 9.BC.10 | Parakeldyshite | Na2ZrSi2O7 |
| 9.BC.10 | Keldyshite | (Na,H)2ZrSi2O7 |
| 9.BC.10 | Khibinskite | K2ZrSi2O7 |
| 9.BC.10 | Brunovskyite | NaZrSi2O6(OH) |
| 9.BC.20 | Barysilite | Pb8Mn2+[Si2O7]3 |
| 9.BC.25 | Edgarbaileyite | [Hg2]2+3[Si2O7] |
| 9.BC.30 | Kristiansenite | Ca4(Sc2Sn2)[Si2O7]2[Si2O6OH]2 |
| 9.BC.30 | Nybergite | Ca4Sc3Sn(Si2O7)(Si2O6OH)3 |
| 9.BC.30 | Silesiaite | Ca4(Fe3+2Sn2)[Si2O7]2[Si2O6OH]2 |
| 9.BC.35 | Percleveite-(Ce) | Ce2Si2O7 |
| 9.BC.35 | Percleveite-(La) | La2Si2O7 |
| 9.BC.40 | Scottyite | BaCu2Si2O7 |
Other Information
Thermal Behaviour:
Unaffected by prolonged heating at 1100 deg
Notes:
It gelatinizes readily in weak HCl-H2SO4 solutions, precipitating abundant gypsum
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 Rankinite
mindat.org URL:
https://www.mindat.org/min-3363.html
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References for Rankinite
Reference List:
Tilley, C. E. (1942) Tricalcium disilicate (rankinite), a new mineral from Scawt Hill, Co. Antrim (With Plate V) Mineralogical Magazine and Journal of the Mineralogical Society, 26 (176) 190-196 doi:10.1180/minmag.1942.026.176.06
Moody, K. M. (1953) The space-group and cell-dimensions of rankinite. Mineralogical Magazine and Journal of the Mineralogical Society, 30 (220) 79 doi:10.1180/minmag.1953.030.220.09
Black, Philippa M. (1969) Rankinite and kilehoanite from Tokatoka, New Zealand. Mineralogical Magazine, 37 (288) 517-519 doi:10.1180/minmag.1969.037.288.13
Henmi, Kitinosuke, Kusachi, Isao, Henmi, Chiyoko (1975) Rankinite and kilchoanite from Fuka, the Town of Bitchu, Okayama Prefecture. Journal of the Mineralogical Society of Japan, 12 (4) 205-214 doi:10.2465/gkk1952.12.205
Kusachi, Isao, Henmi, Chiyoko, Kawahara, Akira, Henmi, Kitinosuke (1975) The structure of rankinite. Mineralogical Journal, 8 (1) 38-47 doi:10.2465/minerj.8.38
SABURI, Shinsuke, KUSACHI, Isao, HENMI, Chiyoko, KAWAHARA, Akira, HENMI, Kitinosuke, KAWADA, Isao (1976) Refinement of the structure of rankinite. Mineralogical Journal, 8 (4) 240-246 doi:10.2465/minerj.8.240
Dowty, Eric (1987) Vibrational interactions of tetrahedra in silicate glasses and crystals. III. Calculations on simple sodium and lithium silicates, thortveitite and rankinite. Physics and Chemistry of Minerals, 14 (6). 542-552 doi:10.1007/bf00308290
Localities for Rankinite
Showing 45 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.
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Caspar quarry, Ettringen, Vordereifel, Mayen-Koblenz, Rhineland-Palatinate, Germany