Alleghanyite
A valid IMA mineral species - grandfathered
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About Alleghanyite
Seal of Alleghany County
Formula:
Mn2+5(SiO4)2(OH)2
Colour:
Pinkish to reddish brown, deep pink, grayish pink
Lustre:
Sub-Vitreous, Resinous, Waxy, Dull
Hardness:
5½
Specific Gravity:
3.93 - 4.02
Crystal System:
Monoclinic
Member of:
Name:
Named in 1932 by Clarence S. Ross and Paul F. Kerr after the type locality occurrence in Alleghany County, North Carolina, USA.
Dimorph of:
Isostructural with:
Alleghanyite is a mineral in the humite group and is the manganese analogue of chondrodite. Alleghnyite is closely related to the other manganese-dominant humite-group minerals such as leucophoenicite, manganhumite and sonolite, and is often difficult to distinguish from these.
Alleghanyite most commonly occurs in hypogene and hydrothermal manganese deposits. It normally occurs as mm-sized grains together with other Mn silicates such as tephroite, but crystals on vein fractures are known from Franklin and Sterling Hill and the Bennalt mine in Wales.
Alleghanyite most commonly occurs in hypogene and hydrothermal manganese deposits. It normally occurs as mm-sized grains together with other Mn silicates such as tephroite, but crystals on vein fractures are known from Franklin and Sterling Hill and the Bennalt mine in Wales.
Unique Identifiers
Mindat ID:
129
Long-form identifier:
mindat:1:1:129:0
IMA Classification of Alleghanyite
Approved, 'Grandfathered' (first described prior to 1959)
Classification of Alleghanyite
9.AF.45
9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination
9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination
52.3.2b.1
52 : NESOSILICATES Insular SiO4 Groups and O,OH,F,H2O
3 : Insular SiO4 Groups and O, OH, F, and H2O with cations in [6] coordination only
52 : NESOSILICATES Insular SiO4 Groups and O,OH,F,H2O
3 : Insular SiO4 Groups and O, OH, F, and H2O with cations in [6] coordination only
14.17.4
14 : Silicates not Containing Aluminum
17 : Silicates of Mn
14 : Silicates not Containing Aluminum
17 : Silicates of Mn
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 |
|---|---|---|
| Alh | 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 Alleghanyite
Sub-Vitreous, Resinous, Waxy, Dull
Transparency:
Transparent, Translucent
Colour:
Pinkish to reddish brown, deep pink, grayish pink
Comment:
in thin section, pink or buff in thick plates
Streak:
Very pale pink
Hardness:
5½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Distinct/Good
Good to poor
Good to poor
Fracture:
Conchoidal, Sub-Conchoidal
Density:
3.93 - 4.02 g/cm3 (Measured) 3.96 g/cm3 (Calculated)
Optical Data of Alleghanyite
Type:
Biaxial (-)
RI values:
nα = 1.756 nβ = 1.780 nγ = 1.792
2V:
Measured: 72° , Calculated: 68°
Birefringence:
0.036
Max. Birefringence:
δ = 0.036
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:
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.
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:
r > v
Optical Extinction:
X ^ a = 35°, Z = b (olivine setting). OAP perpendicular to {100}
Pleochroism:
Weak
Comments:
X brown, Y light brown, Z colorless
Chemistry of Alleghanyite
Mindat Formula:
Mn2+5(SiO4)2(OH)2
Element Weights:
Elements listed:
Common Impurities:
Ti,Al,Fe,Mg,Ca,F
Crystallography of Alleghanyite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/b
Setting:
P21/b
Cell Parameters:
a = 8.27 Å, b = 4.85 Å, c = 10.72 Å
β = 104.64°
β = 104.64°
Ratio:
a:b:c = 1.705 : 1 : 2.21
Unit Cell V:
416.01 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Crystals often rounded, slender; in stout plates, some longitudinally deeply striated. As fan-shaped aggregates; commonly irregular, massive.
Twinning:
On {001} , lamellar, common; also on {105} , {305} .
Comment:
Various settings reported
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) |
|---|---|---|---|---|---|---|---|
| 0000968 | Alleghanyite | Francis C A (1985) Crystal structure refinement of magnesian alleghanyite American Mineralogist 70 182-185 |  | 1985 | Sterling mine, Ogdensburg, New Jersey, USA | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.10 Å | (100) |
| 2.84 Å | (70) |
| 2.75 Å | (40) |
| 2.70 Å | (40) |
| 2.59 Å | (40) |
| 2.33 Å | (50) |
| 1.79 Å | (60) |
Comments:
ICDD 43-683; see also ICDD 39-1348. Older data sets show different strongest lines: ICDD 22-726 (d100 = 1.799) and ICDD 25-1184 (d100 = 3.616).
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 | |
| 32 : Ba/Mn/Pb/Zn deposits, including metamorphic deposits |
Geological Setting:
in veins crosscutting franklinite ore near pegmatites in a metamorphosed stratiform Zn-Mn deposit
Type Occurrence of Alleghanyite
Geological Setting of Type Material:
Hydrothermally deposited, in lenses in a manganese-bearing vein
Associated Minerals at Type Locality:
Synonyms of Alleghanyite
Other Language Names for Alleghanyite
Dutch:Alleghanyiet
French:Alleghanyite
German:Alleghanyit
Norwegian:Alleghanyitt
Russian:Аллеганит
Simplified Chinese:粒硅锰矿
Spanish:Alleghanyita
Relationship of Alleghanyite to other Species
Member of:
Other Members of Manganhumite Subgroup:
| Manganhumite | Mn2+7(SiO4)3(OH)2 | Orth. mmm(2/m2/m2/m) |
| Sonolite | Mn2+9(SiO4)4(OH)2 | Mon. 2/m : P21/b |
Common Associates
Associations Based on Photo Data:
| 25 photos of Alleghanyite associated with Franklinite | Zn2+Fe3+2O4 |
| 20 photos of Alleghanyite associated with Willemite | Zn2SiO4 |
| 20 photos of Alleghanyite associated with Calcite | CaCO3 |
| 9 photos of Alleghanyite associated with Kellyite | Mn2+2Al(AlSiO5)(OH)4 |
| 9 photos of Alleghanyite associated with Kutnohorite | CaMn2+(CO3)2 |
| 7 photos of Alleghanyite associated with Jacobsite | Mn2+Fe3+2O4 |
| 7 photos of Alleghanyite associated with Sussexite | Mn2+BO2(OH) |
| 5 photos of Alleghanyite associated with Pyroxmangite | Mn2+SiO3 |
| 5 photos of Alleghanyite associated with Chlorophoenicite | (Mn,Mg)3Zn2(AsO4)(OH,O)6 |
| 5 photos of Alleghanyite associated with Rhodonite | CaMn3Mn[Si5O15] |
Related Minerals - Strunz-mindat Grouping
| 9.AF. | Chegemite | Ca7(SiO4)3(OH)2 |
| 9.AF. | Jingwenite-(Y) | YAlV4+(SiO4)O2(OH)2 |
| 9.AF. | Barwoodite | Mn2+6Nb5+(SiO4)2O3(OH)3 |
| 9.AF.05 | Sillimanite | Al2(SiO4)O |
| 9.AF.05 | 'Xenolite' | Al10Si8O31 |
| 9.AF.10 | Kanonaite | Mn3+Al(SiO4)O |
| 9.AF.10 | Andalusite | Al2(SiO4)O |
| 9.AF.15 | Kyanite | Al2(SiO4)O |
| 9.AF.20 | Krieselite | Al2(GeO4)F2 |
| 9.AF.20 | Mullite | Al4+2xSi2-2xO10-x |
| 9.AF.23 | Boromullite | Al9BSi2O19 |
| 9.AF.25 | Yoderite | Mg(Al,Fe3+)3(SiO4)2O(OH) |
| 9.AF.30 | Zincostaurolite | Zn2Al9Si4O23(OH) |
| 9.AF.30 | Staurolite | Fe2+2Al9Si4O23(OH) |
| 9.AF.30 | Magnesiostaurolite | Mg(Mg,Li)3(Al,Mg)18Si8O44(OH)4 |
| 9.AF.35 | Topaz | Al2(SiO4)(F,OH)2 |
| 9.AF.40 | Norbergite | Mg3(SiO4)F2 |
| 9.AF.45 | Chondrodite | Mg5(SiO4)2F2 |
| 9.AF.45 | Kumtyubeite | Ca5(SiO4)2F2 |
| 9.AF.45 | Reinhardbraunsite | Ca5(SiO4)2(OH,F)2 |
| 9.AF.45 | Hydroxylchondrodite | Mg5(SiO4)2(OH)2 |
| 9.AF.50 | 'Unnamed (Ca-analogue of Humite)' | Ca7(SiO4)4F2 |
| 9.AF.50 | Humite | Mg7(SiO4)3F2 |
| 9.AF.50 | Manganhumite | Mn2+7(SiO4)3(OH)2 |
| 9.AF.50 | 'Unnamed (OH-analogue of humite)' | Mg7(SiO4)3(OH)2 |
| 9.AF.50 | Fluorchegemite | Ca7(SiO4)3F2 |
| 9.AF.55 | Hydroxylclinohumite | Mg9(SiO4)4(OH)2 |
| 9.AF.55 | Clinohumite | Mg9(SiO4)4F2 |
| 9.AF.55 | Sonolite | Mn2+9(SiO4)4(OH)2 |
| 9.AF.60 | Leucophoenicite | Mn2+7(SiO4)3(OH)2 |
| 9.AF.65 | Ribbeite | Mn2+5(SiO4)2(OH)2 |
| 9.AF.70 | Jerrygibbsite | Mn2+9(SiO4)4(OH)2 |
| 9.AF.75 | Franciscanite | Mn2+6(V5+,◻)2(SiO4)2(O,OH)6 |
| 9.AF.75 | Scorticoite | Mn6(Sb,◻)Σ2(SiO4)2O3(OH)3 |
| 9.AF.75 | Welinite | Mn2+6(W6+,Mg)2(SiO4)2(O,OH)6 |
| 9.AF.75 | Örebroite | Mn2+3(Sb5+,Fe3+)(SiO4)(O,OH)3 |
| 9.AF.80 | Ellenbergerite | Mg6(Mg,Ti,Zr,◻)2(Al,Mg)6Si8O28(OH)10 |
| 9.AF.85 | Magnesiochloritoid | MgAl2O(SiO4)(OH)2 |
| 9.AF.85 | Ottrélite | Mn2+Al2O(SiO4)(OH)2 |
| 9.AF.85 | Chloritoid | Fe2+Al2O(SiO4)(OH)2 |
| 9.AF.90 | Olmiite | CaMn2+[SiO3(OH)](OH) |
| 9.AF.90 | Poldervaartite | CaCa[SiO3(OH)](OH) |
| 9.AF.95 | Pilawite-(Y) | Ca2Y2Al4(SiO4)4O2(OH)2 |
Fluorescence of Alleghanyite
Not fluorescent in UV
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 Alleghanyite
mindat.org URL:
https://www.mindat.org/min-129.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Alleghanyite
Reference List:
Ross, Clarence S., Kerr, Paul F. (1932) The manganese minerals of a vein near Bald Knob, North Carolina. American Mineralogist, 17 (1) 1-18
Rogers, Austin F. (1935) The chemical formula and crystal system of alleghanyite. American Mineralogist, 20 (1) 25-35
Cook, David (1969) Sonolite, alleghanyite and leucophoenicite from New Jersey. American Mineralogist, 54 (9-10) 1392-1398
Rentzeperis, P. J. (1970) The crystal structure of alleghanyite, Mn5[(OH)2|(SiO4)2]. Zeitschrift für Kristallographie, 132 (1). 1-18 doi:10.1524/zkri.1970.132.16.1
Localities for Alleghanyite
Showing 102 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.
Austria | |
| Kolitsch et al. (2021) |
| Kolitsch et al. (2019) |
China | |
| Yang Yuchun (1996) |
| Yang Yuchun (1996) |
| Yang Yuchun (1996) +1 other reference |
| Pingyi Wan (2002) |
| Pingyi Wan (2002) |
| Pingyi Wan (2002) |
| Pingyi Wan (2002) | |
| Yang Yuchun (1996) |
| Yuchun Yang (1990) |
| Yang Yuchun (1996) | |
| Yang Yuchun (1996) |
France | |
| Chopin (1978) |
| Chopin (1978) |
| De Ascenção Guedes et al. (2002) |
| Ragu (1994) +1 other reference |
Italy | |
| Bracco (2012) |
| Biagioni et al. (2025) |
Japan | |
| Mayumi Yoshinaga (1963) |
| - (n.d.) |
| MATSUBARA et al. (1996) |
| Masutomi Museum specimen (Kyoto) +1 other reference |
| FUKUOKA et al. (1977) | |
| FUKUOKA et al. (1977) +1 other reference |
| - (n.d.) +1 other reference | |
| University of Tokyo collection | |
| FUKUOKA et al. (1977) +1 other reference | |
| Mayumi Yoshinaga (1963) |
| Katsu Kaneko (1956) |
| - (n.d.) |
| - (n.d.) |
| Toyofumi Yoshimura et al. (1969) |
| Toyofumi Yoshimura et al. (1969) +1 other reference |
| Kaneko (1956) |
| Minakawa et al. (2008) |
| Mayumi Yoshinaga (1963) |
| Toyofumi Yoshimura et al. (1969) |
| Yoshinaga (1963) |
| Yamada (2004) |
| Katsu Kaneko (1956) +1 other reference |
| Akira Kato (2011) | |
| Akira Kato (2011) | |
| Fukuoka (1981) |
| - (n.d.) |
| Symposium sobre yacimientos de manganeso et al. (1956) +1 other reference |
| 加藤昭 (1980) +1 other reference |
| Fukuoka (1981) | |
| Akira Kato (undated manuscript) +2 other references |
| Fukuoka (1981) | |
| Collection of NHM |
| 加藤昭 (1980) |
| - (n.d.) | |
| Yamada (2004) |
| Fukuoka (1981) |
| Lee (1955) +2 other references | |
| Fumitoshi HIROWATARI (1961) +1 other reference |
| Mayumi Yoshinaga (1963) | |
Kazakhstan | |
| Vereshchagin et al. (2019) +2 other references |
Kyrgyzstan | |
| Pautov et al. (1989) |
Namibia | |
| Dunn et al. (1988) +1 other reference |
Romania | |
| Hîrtopanu et al. (2003) | |
| Udubasa et al. (1996) +3 other references |
| minerals-of-the-carpathians.eu (2008) |
Russia | |
| Brusnitsyn et al. (2002) +1 other reference |
| Brusnitsyn +1 other reference |
| Старикова (2011) |
| Brusnitsyn (2000) |
| Brusnitsyn A.I. (2000) |
Slovakia | |
| Radvanec M. and Gonda S. (2020) |
South Africa | |
| XRD and SEM-EDS by Joy Desor and ... |
Spain | |
| Calvo Rebollar (2025) |
| Dill et al. (2023) |
| Dill et al. (2023) |
Sweden | |
| Nysten (2003) +1 other reference |
| Gatedal (n.d.) +1 other reference |
| Gatedal (n.d.) +1 other reference | |
| Mineralogical Society of America - ... +1 other reference | |
| Nysten (2004) |
Switzerland | |
| Stalder et al. (1998) |
| Stalder et al. (1998) +1 other reference |
| Stalder et al. (1998) |
| Ansermet et al. (2021) |
| Stalder et al. (1998) |
UK | |
| Bevins (1994) +1 other reference |
| Cotterell (2013) |
USA | |
| Hewett et al. (1961) +3 other references |
| Hewett et al. (1961) +2 other references | |
| Flohr et al. (1992) |
| Flohr et al. (1992) | |
| Rogers (1919) +5 other references |
| Burbank (1933) +1 other reference |
| Schooner (circa 1980s) |
| Anthony (1997) |
| Quinn (1945) |
| Palache (1928) +3 other references |
| Cook (1969) +3 other references |
| Ross et al. (1932) +2 other references |
| Dietrich (1990) |
| Tracy et al. (2003) |
| Cannon (1975) |
| Cannon (1975) |
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Sterling Mine, Sterling Hill, Ogdensburg, Sussex County, New Jersey, USA