Log In
Homilite
A valid IMA mineral species - grandfathered
This page is currently not sponsored. Click here to sponsor this page.
About Homilite
Formula:
Ca2(Fe2+,Mg)B2Si2O10
Colour:
Greenish black to brownish black
Lustre:
Vitreous, Resinous
Hardness:
5 - 5½
Specific Gravity:
3.34
Crystal System:
Monoclinic
Member of:
Name:
Named by Sigurd Reinhold Paijkull (1849-1884) from the Greek ὁμιλέω, "to occur together," in allusion to its association with meliphanite and "erdmannite".
Type Locality:
A borosilicate mineral belonging to the datolite subgroup of the gadolinite group of the gadolinite supergroup. Crystals of homilite was first noticed from Stokkøya, Langesundsfjorden, Norway by A. E. Nordenskiöld in 1860, but it was first published and described by S.R.Paijkull (1876). Brøgger (1890) published extensive crystallographic data. The structure was solved by Miyawaki et al. (1985) on the material from type locality.
In the Langesundsfjorden area, Norway it occurs in syenite pegmatites, exclusively within the "meliphanite zone", a zone strecthing across the central parts of the Stokkøya and Arøya Island. Homilite was also discovered in a volcanic ejectum at Tre Croci, Vico volcanic complex, Viterbo Province, Latium, Italy in 2004 (Pierini 2004).
In the Langesundsfjorden area, Norway it occurs in syenite pegmatites, exclusively within the "meliphanite zone", a zone strecthing across the central parts of the Stokkøya and Arøya Island. Homilite was also discovered in a volcanic ejectum at Tre Croci, Vico volcanic complex, Viterbo Province, Latium, Italy in 2004 (Pierini 2004).
Unique Identifiers
Mindat ID:
1926
Long-form identifier:
mindat:1:1:1926:8
Similar Names
IMA Classification of Homilite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Ca2Fe2+B2(SiO4)2O2
First published:
1876
Classification of Homilite
9.AJ.20
9 : SILICATES (Germanates)
A : Nesosilicates
J : Nesosilicates with BO3 triangles and/or B[4], Be[4] tetrahedra, cornersharing with SiO4
9 : SILICATES (Germanates)
A : Nesosilicates
J : Nesosilicates with BO3 triangles and/or B[4], Be[4] tetrahedra, cornersharing with SiO4
54.2.1b.5
54 : NESOSILICATES Borosilicates and Some Beryllosilicates
2 : Borosilicates and Some Beryllosilicates with B in [4] coordination
54 : NESOSILICATES Borosilicates and Some Beryllosilicates
2 : Borosilicates and Some Beryllosilicates with B in [4] coordination
17.5.48
17 : Silicates Containing other Anions
5 : Borosilicates
17 : Silicates Containing other Anions
5 : Borosilicates
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 |
|---|---|---|
| Hom | 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 Homilite
Vitreous, Resinous
Transparency:
Opaque
Colour:
Greenish black to brownish black
Comment:
Translucent in very thin splinters
Streak:
Grey
Hardness:
5 - 5½ on Mohs scale
Tenacity:
Brittle
Cleavage:
None Observed
Fracture:
Sub-Conchoidal
Density:
3.34 g/cm3 (Measured)
Optical Data of Homilite
Type:
Biaxial (+)
RI values:
nα = 1.715 nβ = 1.725 nγ = 1.738
2V:
Measured: 80° , Calculated: 84°
Max. Birefringence:
δ = 0.023
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:
none
Optical Extinction:
Z = b; Y ∧ c = -1°.
Comments:
Absorption: Y > X > Z.
Chemistry of Homilite
Mindat Formula:
Ca2(Fe2+,Mg)B2Si2O10
Element Weights:
Common Impurities:
Al,Mn,Na
Chemical Analysis
Oxide wt%:
| 1 | 2 | |
|---|---|---|
| SiO2 | 31.87 % | 31.58 % |
| B2O3 by difference | 18.08 % | 21.46 % |
| FeO | 16.25 % | 17.03 % |
| Fe2O3 | 2.15 % | |
| Al2O3 | 1.50 % | |
| CaO | 27.28 % | 29.43 % |
| MgO | 0.52 % | |
| Na2O | 1.50 % | |
| K2O | 0.41 % | |
| LOI | 0.85 % | |
| MnO | 0.50 % | |
| Total: | 100.41 % | 100 % |
Sample references:
| ID | Type | Locality | Reference | Notes |
|---|---|---|---|---|
| 1 | Type Specimen | Stokkøya, Larvik Commune, Vestfold, Norway | Wet-chemical analysis | |
| 2 | " " | Electron microprobe |
Crystallography of Homilite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/b
Setting:
P21/a
Cell Parameters:
a = 9.78 Å, b = 7.61 Å, c = 4.78 Å
β = 90.56°
β = 90.56°
Ratio:
a:b:c = 1.285 : 1 : 0.628
Unit Cell V:
355.74 ų (Calculated from Unit Cell)
Morphology:
Observed forms (after Brögger 1890): {001}, {011}, {021}, {010}, {100}, {720}, {310}, {210}, {110}, {890}, {120}, {201}, {111}, {211}, {111}, {421}, {221}, {10·5·2}.
Twinning:
Frequently occurs as twins: with (100) as the twin plane, with (001) as the twin plane, with (430) as the twin pane or with (120) as the twin plane.
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
Remove metal-metal sticks
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) |
|---|---|---|---|---|---|---|---|
| 0010002 | Homilite | Miyawaki R, Nakai I, Nagashima K (1985) Structure of homilite, Ca2.00(Fe0.90Mn0.03)B2.00Si2.00O9.86(OH)0.14 Acta Crystallographica C41 13-15 |  | 1985 | Stoko, Brevig, Langesundfjord, Norway | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.10 Å | (100) |
| 2.52 Å | (100) |
| 2.83 Å | (90) |
| 2.97 Å | (70) |
| 2.18 Å | (70) |
| 2.23 Å | (60) |
| 1.86 Å | (50) |
Comments:
Store-Arø Island, Langesundsfjord, Norway. ICDD 17-211.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 35 : Ultra-alkali and agpaitic igneous rocks |
Geological Setting:
syenite pegmatite
Type Occurrence of Homilite
General Appearance of Type Material:
Black to black-brownish crystal
Place of Conservation of Type Material:
Muséum National d’Histoire Naturelle, Galerie Nationale de Minéralogie et de Géologie, Paris, France (catalogue #78142), Naturhistoriske Riksmuseet, Sektionen för Mineralogi, Stockholm, Sweden (catalogue # 531010)
Geological Setting of Type Material:
Nepheline syenite pegmatite
Associated Minerals at Type Locality:
Other Language Names for Homilite
Relationship of Homilite to other Species
Common Associates
Associations Based on Photo Data:
| 4 photos of Homilite associated with Meliphanite | (Ca,Na)2(Be,Al)[Si2O6(OH,F)] |
| 2 photos of Homilite associated with Titanite | CaTiO(SiO4) |
| 2 photos of Homilite associated with Microcline | K(AlSi3O8) |
| 1 photo of Homilite associated with Zircon | Zr(SiO4) |
Related Minerals - Strunz-mindat Grouping
| 9.AJ. | Hingganite-(Nd) | Nd2◻Be2Si2O8(OH)2 |
| 9.AJ. | Arrheniusite-(Ce) | CaMg[(Ce7Y3)Ca5](SiO4)4(Si2B3AsO18)(BO3)F11 |
| 9.AJ.05 | Ominelite | (Fe2+,Mg)(Al,Fe3+)3(SiO4)(BO3)O2 |
| 9.AJ.05 | Grandidierite | (Mg,Fe2+)(Al,Fe3+)3(SiO4)(BO3)O2 |
| 9.AJ.10 | Dumortierite | Al(Al2O)(Al2O)2(SiO4)3(BO3) |
| 9.AJ.10 | Nioboholtite | (Nb0.6◻0.4)Al6BSi3O18 |
| 9.AJ.10 | Titanoholtite | (Ti0.75◻0.25)Al6BSi3O18 |
| 9.AJ.10 | Holtite | (Ta0.6◻0.4)Al6BSi3O18(O,OH)2.25 |
| 9.AJ.10 | Magnesiodumortierite | Mg(Al2OH)(Al2O)2(SiO4)3(BO3) |
| 9.AJ.15 | Garrelsite | Ba3NaSi2B7O16(OH)4 |
| 9.AJ.20 | 'Muromontite' | near Be2FeY2Si3O12 |
| 9.AJ.20 | Gadolinite-(Nd) | Nd2Fe2+Be2O2(SiO4)2 |
| 9.AJ.20 | Datolite | CaB(SiO4)(OH) |
| 9.AJ.20 | Melanocerite-(Ce) | (Ce,Ca)5(SiO4,BO4)3(OH,O) |
| 9.AJ.20 | Gadolinite-(Ce) | (Ce,La,Nd,Y)2Fe2+Be2Si2O10 |
| 9.AJ.20 | Gadolinite-(Y) | Y2Fe2+Be2Si2O10 |
| 9.AJ.20 | 'Unnamed (OH-analogue of Gadolinite-(Y))' | (Y,Ca)2(Fe,◻)Be2Si2O8(OH,O)2 |
| 9.AJ.20 | Hingganite-(Ce) | (Ce,REE)2(◻,Fe2+)Be2[SiO4]2(OH)2 |
| 9.AJ.20 | Hingganite-(Y) | (Y,REE,Ca)2(◻,Fe2+)Be2[SiO4]2(OH)2 |
| 9.AJ.20 | Hingganite-(Yb) | (Yb,Y,REE)2◻Be2[SiO4]2(OH)2 |
| 9.AJ.20 | 'Minasgeraisite-(Y)' | (Ca2Y2)◻2(Be2B2)[SiO4]4(OH)4 |
| 9.AJ.20 | Calcybeborosilite-(Y) | (Y,Ca)2(◻,Fe2+)(B,Be)2[SiO4]2(OH,O)2 |
| 9.AJ.25 | Stillwellite-(La) | LaBSiO5 |
| 9.AJ.25 | Stillwellite-(Ce) | (Ce,La,Ca)BSiO5 |
| 9.AJ.30 | Cappelenite-(Y) | Ba(Y,Ce)6Si3B6O24F2 |
| 9.AJ.35 | Laptevite-(Ce) | Ca6(Fe2+,Mn2+)Y3REE7(SiO4)3(PO4)(B3Si3O18)(BO3)F11 |
| 9.AJ.35 | Proshchenkoite-(Y) | Ca(Y,REE,Ca,Na,Mn)15Fe2+(P,Si)Si6B3O34F14 |
| 9.AJ.35 | Okanoganite-(Y) | (Na,Ca)3(Y,Ce)12Si6B2O27F14 |
| 9.AJ.35 | Hundholmenite-(Y) | (Y,REE,Ca,Na)15(Al,Fe3+)(CaxAs3+1-x)(Si,As5+)Si6B3(O,F)48 |
| 9.AJ.35 | Vicanite-(Ce) | (Ca,Ce,La,Th)15As5+(As3+0.5,Na0.5)Fe3+Si6B4O40F7 |
| 9.AJ.40 | Jadarite | LiNaSiB3O7(OH) |
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 Homilite
mindat.org URL:
https://www.mindat.org/min-1926.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
External Links:
Mineral Dealers:
References for Homilite
Reference List:
Paijkull, S. R. (1876) Homilit, ett mineral från Brevig i Norge. Geologiska Föreningen i Stockholm Förhandlingar, 3 (7) 229-232 doi:10.1080/11035897609446186
Localities for Homilite
Showing 13 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.
Italy | |
| Pierini (2004) +1 other reference |
Norway | |
| Larsen et al. (2010) |
| Brøgger (1890) | |
| Paijkull (1876) +1 other reference | |
| Naturhistorska Riskmuseets Stockholm ... +1 other reference |
| Brøgger (1890) |
| Åsheim et al. (1980) | |
| Nordrum (2001) |
| Hansen (1981) |
Romania | |
| minerals-of-the-carpathians.eu (2008) |
| Hîrtopanu (1997) +1 other reference |
Sweden | |
| Probed 2004 - M.E. Ciriotti |
Quick NavTopAbout HomiliteUnique IdentifiersSimilar NamesIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Chemical AnalysisCrystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence Other LanguagesRelationshipsCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
Stokksund, Larvik Commune, Vestfold, Norway