Osumilite (original) (raw)

A valid IMA mineral species - grandfathered

About OsumiliteHide

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Formula:

K◻2Fe2+2Al3[Al2Si10O30]

some Na reported in the B site (dominated by ◻ in the end-member formula);
some Mg reported in the A site (dominated by Fe in the end-member formula)

Colour:

Black, dark blue, dark brown, pink, gray

Specific Gravity:

2.58 - 2.68

Name:

Named in 1953 by Akiho Miyashiro for the Osumi Peninsula, Japan, on which the type locality is found.

Osumilite Group.

Difficult to distinguish from Osumilite-(Mg).

Compare 'UM1984-35-SiO:AlCaFeKMg'.

From Belakovskiy (2013), summarizing Chukanov et al. (2013):
"Chemical data for osumilite in original paper (Miyashiro 1956) show that it is Mg‑dominant. However this analysis shows the sum of cations Si+Al+Fe+Mg+Mn (for O = 30) is 0.78 more then the theoretical value. The study of osumilite type locality material (Armbruster and Oberhänsli 1988; abstracted paper) show the significant Fe2+ prevalence over Mg. Anyway, the name osumilite had been assigned by IMA CNMNC Fe2+-dominant osumilite."

Unique IdentifiersHide

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Long-form identifier:

mindat:1:1:3039:3

134ee8fe-98fe-4468-a169-e88e227da07b

IMA Classification of OsumiliteHide

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Approved, 'Grandfathered' (first described prior to 1959)

IMA Formula:

KFe2(Al5Si10)O30

Type description reference:

Classification of OsumiliteHide

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9.CM.05

9 : SILICATES (Germanates)
C : Cyclosilicates
M : [Si6O18]12- 6-membered double rings (sechser-Doppelringe)

63.2.1a.6

63 : CYCLOSILICATES Condensed Rings
2 : Condensed Rings (Milarite - Osumilite group)

16.24.16

16 : Silicates Containing Aluminum and other Metals
24 : Aluminosilicates of Fe, Mg, Ca and alkalis

Mineral SymbolsHide

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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.

Physical Properties of OsumiliteHide

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Transparency:

Transparent, Translucent

Colour:

Black, dark blue, dark brown, pink, gray

Comment:

Strongly pleochroic

Cleavage:

Poor/Indistinct
Indistinct, parallel and perpendicular {0001}

Density:

2.58 - 2.68 g/cm3 (Measured) 2.71 g/cm3 (Calculated)

Optical Data of OsumiliteHide

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RI values:

_n_ω = 1.539 - 1.547 _n_ε = 1.545 - 1.551

2V:

Measured: 28° to 45°, Calculated: 0.0° to 0.0°

δ = 0.006

Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.

Optical Extinction:

Nominally uniaxial(+/-), but may be anomalously biaxial (+/-) with a 2V° from 0 (so true uniaxial) up to ~45°.

Comments:

O = light blue to bluish purple, pale pink, pale yellow-brown; E = colorless to brown.

Comments:

Anomalously biaxial.

Chemistry of OsumiliteHide

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Mindat Formula:

K◻2Fe2+2Al3[Al2Si10O30]

some Na reported in the B site (dominated by ◻ in the end-member formula);
some Mg reported in the A site (dominated by Fe in the end-member formula)

Common Impurities:

Ti,Mn,Ba,Na,Mg

Crystallography of OsumiliteHide

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Class (H-M):

6/m m m _(_6/_m_2/_m_2/m ) - Dihexagonal Dipyramidal

Cell Parameters:

a = 10.13(4) Å, c = 14.31(5) Å

Unit Cell V:

1,271.71 ų (Calculated from Unit Cell)

Morphology:

Hexagonal, tabular. Well developed {0001}, {1010}, {1120}. Also {2130}, {1011}, {1012}, {1122}.

Twinning:

Rarely, perpendicular to {0001}.

Crystal StructureHide

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ID	Species	Reference	Link	Year	Locality	Pressure (GPa)	Temp (K)
0000078	Osumilite	Miyashiro A (1956) Osumilite, a new silicate mineral, and its crystal structure American Mineralogist 41 104-116		1956	0	293
0000188	Osumilite	Brown G E, Gibbs G V (1969) Refinement of the crystal structure of osumilite American Mineralogist 54 101-116		1969	0	293
0001149	Osumilite	Armbruster T, Oberhansli R (1988) Crystal chemistry of double-ring silicates: Structural, chemical, and optical variation in osumilites American Mineralogist 73 585-594		1988	0	293
0001150	Osumilite	Armbruster T, Oberhansli R (1988) Crystal chemistry of double-ring silicates: Structural, chemical, and optical variation in osumilites American Mineralogist 73 585-594		1988	0	293
0001151	Osumilite	Armbruster T, Oberhansli R (1988) Crystal chemistry of double-ring silicates: Structural, chemical, and optical variation in osumilites American Mineralogist 73 585-594		1988	0	293
0001152	Osumilite	Armbruster T, Oberhansli R (1988) Crystal chemistry of double-ring silicates: Structural, chemical, and optical variation in osumilites American Mineralogist 73 585-594		1988	0	293
0001153	Osumilite	Armbruster T, Oberhansli R (1988) Crystal chemistry of double-ring silicates: Structural, chemical, and optical variation in osumilites American Mineralogist 73 585-594		1988	0	293
0001154	Osumilite	Armbruster T, Oberhansli R (1988) Crystal chemistry of double-ring silicates: Structural, chemical, and optical variation in osumilites Japan-Hayasaki American Mineralogist 73 585-594		1988	0	293
0001155	Osumilite	Armbruster T, Oberhansli R (1988) Crystal chemistry of double-ring silicates: Structural, chemical, and optical variation in osumilites American Mineralogist 73 585-594		1988	0	293
0001156	Osumilite	Armbruster T, Oberhansli R (1988) Crystal chemistry of double-ring silicates: Structural, chemical, and optical variation in osumilites American Mineralogist 73 585-594		1988	0	293
0006584	Osumilite	Winter W, Armbruster T, Lengauer C (1995) Crystal structure refinement of synthetic osumilite-type phases: BaMg2Al6Si9O30, SrMg2Al6Si9O30 and Mg2Al4Si11O30 European Journal of Mineralogy 7 277-286	1995	0	293
0006585	Osumilite	Winter W, Armbruster T, Lengauer C (1995) Crystal structure refinement of synthetic osumilite-type phases: BaMg2Al6Si9O30, SrMg2Al6Si9O30 and Mg2Al4Si11O30 European Journal of Mineralogy 7 277-286	1995	0	293
0006586	Osumilite	Winter W, Armbruster T, Lengauer C (1995) Crystal structure refinement of synthetic osumilite-type phases: BaMg2Al6Si9O30, SrMg2Al6Si9O30 and Mg2Al4Si11O30 European Journal of Mineralogy 7 277-286	1995	0	293
0007256	Osumilite	Seryotkin Y V, Sokol E V, Bakakin V V, Likhacheva A Y (2008) Pyrometamorphic osumilite: occurrence, paragenesis, and crystal structure as compared to cordierite European Journal of Mineralogy 20 191-198	2008	South Urals, Russia	0	293
0007263	Osumilite	Balassone G, Mormone A, Rossi M, Bernardi A, Fisch M, Armbruster T, Malsy K, Berger A (2008) Crystal chemical and structural characterization of an Mg-rich osumilite from Vesuvius volcano (Italy) European Journal of Mineralogy 20 713-720	2008	Vesuvius volcano, Italy	0	293

CIF Raw Data - click here to close

X-Ray Powder DiffractionHide

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Powder Diffraction Data:

Comments:

Nearly identical to merrihueite.

Geological EnvironmentHide

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Type Occurrence of OsumiliteHide

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General Appearance of Type Material:

In crystals, a few millimeters or less in size, black to the unaided eye, and prismatic or tabular in habit. Previously mistaken for cordierite.

Place of Conservation of Type Material:

Harvard University, Cambridge, Massachusetts, USA, 104744.

Geological Setting of Type Material:

Biotite-bearing hypersthene-plagioliparite (rhyodacite).

Reference:

Miyashiro, A. (1953) Osumilite, a new mineral, and cordierite in volcanic rocks. Proceedings of the Japan Academy: 29(7): 321-323.

Synonyms of OsumiliteHide

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Other Language Names for OsumiliteHide

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Relationship of Osumilite to other SpeciesHide

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Other Members of this group:

Common AssociatesHide

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Associated Minerals Based on Photo Data:

Related Minerals - Strunz-mindat GroupingHide

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Other InformationHide

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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 OsumiliteHide

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References for OsumiliteHide

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Reference List:

Balassone, Giuseppina, Mormone, Angela, Rossi, Manuela, Bernardi, Alessandro, Fisch, Martin, Armbruster, Thomas, Malsy, Anna, Kathrin Berger, Alfons (2008) Crystal chemical and structural characterization of an Mg-rich osumilite from Vesuvius volcano (Italy) European Journal of Mineralogy, 20 (5) 713-720 doi:10.1127/0935-1221/2008/0020-1839

Chukanov, N. V., Pekov, I. V., Rastsvetaeva, R. K., Aksenov, S. M., Belakovskiy, D. I., Van, K. V., Schüller, W., Ternes, B. (2013) Osumilite-(Mg): Validation as a mineral species and new data. Geology of Ore Deposits, 55 (7) 587-593 doi:10.1134/s1075701513070064

Localities for OsumiliteHide

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This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

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- 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). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).

All localities listed without proper references should be considered as questionable.