Moydite-(Y)
A valid IMA mineral species
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About Moydite-(Y)
Louis Moyd
Formula:
Y[B(OH)4](CO3)
Colour:
Yellow, also colorless
Lustre:
Vitreous, Sub-Vitreous
Hardness:
1 - 2
Specific Gravity:
3.133
Crystal System:
Orthorhombic
Name:
Named moydite in 1986 by Joel D. Grice, Jerry Van Velthuizen, Pete J. Dunn, D. E. Newbury, E. S. Etz, and C. H. Nielsen, in honor of Luis Moyd [March 13, 1916 Philadelphia, PA, USA - February 4, 2006 Ottawa, Ontario, Canada], curator of mineralogy, National Museums of Canada. The suffix/modifier was added a year later, following the Levinson rule for species with essential REE indicating, in this case, predominant yttrium.
Unique Identifiers
Mindat ID:
2798
Long-form identifier:
mindat:1:1:2798:0
Similar Names
| Boydite | A synonym of Probertite | |
| Medaite | A valid IMA mineral species | Mn62+V5+Si5O18(OH) |
IMA Classification of Moydite-(Y)
Classification of Moydite-(Y)
6.AC.45
6 : BORATES
A : Monoborates
C : B(O,OH)4, without and with additional anions; 1(T), 1(T)+OH, etc
6 : BORATES
A : Monoborates
C : B(O,OH)4, without and with additional anions; 1(T), 1(T)+OH, etc
27.1.9.1
27 : COMPOUND BORATES
1 : Miscellaneous
27 : COMPOUND BORATES
1 : Miscellaneous
10.4.5
10 : Borates with other anions
4 : Borates with carbonate
10 : Borates with other anions
4 : Borates with carbonate
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 |
|---|---|---|
| Moy-Y | 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 Moydite-(Y)
Vitreous, Sub-Vitreous
Transparency:
Transparent
Colour:
Yellow, also colorless
Streak:
Pale yellow to colorless
Hardness:
1 - 2 on Mohs scale
Comment:
"Soft", Probably harder than 2
Tenacity:
Brittle
Cleavage:
Distinct/Good
{010} good; {101} poor
{010} good; {101} poor
Fracture:
Conchoidal
Density:
3.133 g/cm3 (Measured) 3.018 g/cm3 (Calculated)
Optical Data of Moydite-(Y)
Type:
Biaxial (-)
RI values:
nα = 1.588 nβ = 1.681 nγ = 1.690
2V:
Measured: 32° , Calculated: 34°
Birefringence:
0.102
Max. Birefringence:
δ = 0.102
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:
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.
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.
Dispersion:
relatively strong
Optical Extinction:
Parallel. X = b; Y = a; Z = c.
Pleochroism:
Non-pleochroic
Chemistry of Moydite-(Y)
Mindat Formula:
Y[B(OH)4](CO3)
Element Weights:
Common Impurities:
REE
Crystallography of Moydite-(Y)
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Pbca
Setting:
Pbca
Cell Parameters:
a = 9.089 Å, b = 12.244 Å, c = 8.926 Å
Ratio:
a:b:c = 0.742 : 1 : 0.729
Unit Cell V:
993.34 ų (Calculated from Unit Cell)
Z:
8
Morphology:
Type material: Platy basal pinacoid {010} modified by the rhombic dipyramid {111} and, occasionally, a minor development of pinacoids {100} and {001}.
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
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Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
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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) |
|---|---|---|---|---|---|---|---|
| 0005214 | Moydite-(Y) | Grice J D, Ercit T S (1986) The crystal structure of moydite The Canadian Mineralogist 24 675-678 |  | 1986 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 6.106 Å | (100) |
| 4.501 Å | (90) |
| 3.179 Å | (70) |
| 2.818 Å | (50) |
| 2.749 Å | (30) |
| 2.525 Å | (40) |
| 2.203 Å | (30) |
Comments:
Evans-Lou Mine, Québec, Canada. Data from the type description.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 22 : Hydration and low-? subsurface aqueous alteration (see also #23) |
Type Occurrence of Moydite-(Y)
General Appearance of Type Material:
Yellow bladed gemmy crystals to 1 mm+.
Place of Conservation of Type Material:
Canadian Museum of Nature, Ottawa, Canada, numbers 50771 and 50772 (holotype and cotype).
National Museum of Natural History, Washington, D.C., USA, number 162936 (cotype).
National Museum of Natural History, Washington, D.C., USA, number 162936 (cotype).
Geological Setting of Type Material:
Granite pegmatite rich in rare earth minerals.
Associated Minerals at Type Locality:
Synonyms of Moydite-(Y)
Other Language Names for Moydite-(Y)
Related Minerals - Strunz-mindat Grouping
| 6.AC.05 | Sinhalite | MgAl(BO4) |
| 6.AC.10 | Pseudosinhalite | Mg2Al3(BO3)2(OH)O3 |
| 6.AC.15 | Béhierite | Ta(BO4) |
| 6.AC.15 | Schiavinatoite | Nb(BO4) |
| 6.AC.20 | Frolovite | Ca[B(OH)4]2 |
| 6.AC.25 | Hexahydroborite | Ca[B(OH)4]2 · 2H2O or CaB2O4 · 6H2O |
| 6.AC.30 | Henmilite | Ca2Cu[B(OH)4]2(OH)4 |
| 6.AC.35 | Bandylite | Cu[B(OH)4]Cl |
| 6.AC.40 | Teepleite | Na2[B(OH)4]Cl |
| 6.AC.50 | Carboborite | Ca2Mg[B(OH)4]2(CO3)2 · 4H2O |
| 6.AC.55 | Sulfoborite | Mg3[B(OH)4]2(SO4)(OH,F)2 |
| 6.AC.60 | Lüneburgite | Mg3[B2(OH)6](PO4)2 · 6H2O |
| 6.AC.65 | Seamanite | Mn2+3[B(OH)4](PO4)(OH)2 |
| 6.AC.70 | Cahnite | Ca2[B(OH)4](AsO4) |
Fluorescence of Moydite-(Y)
Not fluorescent.
Other Information
Notes:
Not readily soluble in 30% HCl.
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 Moydite-(Y)
mindat.org URL:
https://www.mindat.org/min-2798.html
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Please feel free to link to this page.
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References for Moydite-(Y)
Localities for Moydite-(Y)
Showing 2 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 | |
| Kolitsch et al. (2026) |
Canada (TL) | |
| Grice et al. (1986) |
Quick NavTopAbout Moydite-(Y)Unique IdentifiersSimilar NamesIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesStrunz-MindatFluorescence Other InformationInternet Links References Localities Locality List
Evans-Lou Mine, Lake Saint-Pierre, Saint-Pierre-de-Wakefield, Val-des-Monts, Les Collines-de-l'Outaouais RCM, Outaouais, Québec, Canada