Offretite
A valid IMA mineral species - grandfathered
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About Offretite
Albert J. J. Offret
Formula:
KCaMg(Si13Al5)O36 · 15H2O
Colour:
Colorless, white
Lustre:
Vitreous
Hardness:
4 - 4½
Specific Gravity:
2.13
Crystal System:
Hexagonal
Member of:
Name:
Named in honor of Albert Jules Joseph Offret (24 October 1857, Douai, France - 4 March 1933, Lyon, France), professor at the University of Lyon, France.
Zeolite Group.
A zeolite difficult to distinguish from erionite.
NOTE: The zeolite mineral species epitaxially overgrown on lévyne in all cases is identified as erionite (Passaglia et al., 1998).
A zeolite difficult to distinguish from erionite.
NOTE: The zeolite mineral species epitaxially overgrown on lévyne in all cases is identified as erionite (Passaglia et al., 1998).
Unique Identifiers
Mindat ID:
2960
Long-form identifier:
mindat:1:1:2960:1
IMA Classification of Offretite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
KCaMg(Si13Al5)O36·15H2O
First published:
1890
Classification of Offretite
9.GD.25
9 : SILICATES (Germanates)
G : Tektosilicates with zeolitic H2O; zeolite family
D : Chains of 6-membered rings – tabular zeolites
9 : SILICATES (Germanates)
G : Tektosilicates with zeolitic H2O; zeolite family
D : Chains of 6-membered rings – tabular zeolites
77.1.2.4
77 : TECTOSILICATES Zeolites
1 : Zeolite group - True zeolites
77 : TECTOSILICATES Zeolites
1 : Zeolite group - True zeolites
16.10.23
16 : Silicates Containing Aluminum and other Metals
10 : Aluminosilicates of Ca and alkalis
16 : Silicates Containing Aluminum and other Metals
10 : Aluminosilicates of Ca and alkalis
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 |
|---|---|---|
| Off | 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 Offretite
Vitreous
Transparency:
Transparent, Translucent
Colour:
Colorless, white
Streak:
White
Hardness:
4 - 4½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Distinct/Good
{0001}
{0001}
Fracture:
Irregular/Uneven
Density:
2.13 g/cm3 (Measured) 2.06 g/cm3 (Calculated)
Optical Data of Offretite
Type:
Uniaxial (-)
RI values:
nω = 1.489 - 1.495 nε = 1.486 - 1.492
Max. Birefringence:
δ = 0.003
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 (negative)
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 uniaxial interference figure - the conoscopic
(convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis
centred and vertical. The coloured rings are isochromatics, computed with the
same physics as the Michel-Lévy bar above; the dark cross is the isogyre.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
Chemistry of Offretite
Mindat Formula:
KCaMg(Si13Al5)O36 · 15H2O
Element Weights:
Common Impurities:
Mg
Crystallography of Offretite
Crystal System:
Hexagonal
Class (H-M):
6m2 - Ditrigonal Dipyramidal
Space Group:
P6m2
Cell Parameters:
a = 13.291(2) Å, c = 7.582(6) Å
Ratio:
a:c = 1 : 0.57
Unit Cell V:
1,159.92 ų (Calculated from Unit Cell)
Z:
1
Morphology:
Hexagonal prisms
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) |
|---|---|---|---|---|---|---|---|
| 0002007 | Offretite | Gualtieri A, Artioli G, Passaglia E, Bigi S, Viani A, Hanson J C (1998) Crystal structure-crystal chemistry relationships in the zeolites erionite and offretite Sample #2 from Fitta American Mineralogist 83 590-606 |  | 1998 | 0 | 293 | |
| 0002006 | Offretite | Gualtieri A, Artioli G, Passaglia E, Bigi S, Viani A, Hanson J C (1998) Crystal structure-crystal chemistry relationships in the zeolites erionite and offretite Sample #1 from Fitta American Mineralogist 83 590-606 | | 1998 | 0 | 293 | |
| 0002005 | Offretite | Gualtieri A, Artioli G, Passaglia E, Bigi S, Viani A, Hanson J C (1998) Crystal structure-crystal chemistry relationships in the zeolites erionite and offretite Sample from Mt. Semiol American Mineralogist 83 590-606 | | 1998 | 0 | 293 |
CIF Raw Data - click here to close
Epitaxial Relationships of Offretite
Epitaxial Minerals:
| Erionite Subgroup | M2[Al4Si14O36] · 15H2O |
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 11.50 Å | (100) |
| 2.880 Å | (64) |
| 4.352 Å | (59) |
| 3.837 Å | (43) |
| 5.76 Å | (35) |
| 3.322 Å | (22) |
| 6.64 Å | (20) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 3a: Earth’s earliest Hadean crust | >4.50 |
| 10 : Basalt-hosted zeolite minerals |
Type Occurrence of Offretite
General Appearance of Type Material:
Colorless hexagonal crystals to 1 mm. Also in radiating hemispheres and as druses. Crystals are sometimes slightly barrel shaped.
Geological Setting of Type Material:
Basalt
Associated Minerals at Type Locality:
Synonyms of Offretite
Other Language Names for Offretite
Relationship of Offretite to other Species
Member of:
Other Members of Zeolite Group:
| Alflarsenite | NaCa2Be3Si4O13(OH) · 2H2O | Mon. 2 : P21 |
| Amicite | K2Na2Al4Si4O16 · 5H2O | Mon. 2 |
| Ammonioleucite | (NH4)(AlSi2O6) | Tet. 4/m : I41/a |
| Analcime | Na(AlSi2O6) · H2O | Tric. 1 : P1 |
| Arzamastsevite | K6Al5Si6O20(OH)4Cl | Tet. 42m : I42m |
| Bellbergite | (K,Ba,Sr)2Sr2Ca2(Ca,Na)4[Al3Si3O12]6 · 30H2O | Hex. |
| Bikitaite | LiAlSi2O6 · H2O | Tric. 1 : P1 |
| Boggsite | Ca8Na3(Si,Al)96O192 · 70H2O | Orth. mmm(2/m2/m2/m) : Imma |
| Brewsterite Subgroup | Zeolite Group. | |
| Chabazite-Levyne Subgroup | M[Al2Si4O12] · 6H2O | |
| Chiavennite | CaMnBe2Si5O13(OH)2 · 2H2O | Mon. 2/m : P21/b |
| Clinoptilolite Subgroup | (Na/Ca/K)3-6[Al6-7Si29-30O72] · 20H2O | |
| Cowlesite | CaAl2Si3O10 · 6H2O | Orth. mmm(2/m2/m2/m) |
| Dachiardite Subgroup | Zeolite Group. | |
| Direnzoite | NaK6MgCa2(Al13Si47O120) · 36H2O | Orth. mmm(2/m2/m2/m) : Pmmn |
| Edingtonite | Ba[Al2Si3O10] · 4H2O | Orth. 222 : P212121 |
| Epistilbite | CaAl2Si6O16 · 5H2O | Mon. |
| Erionite Subgroup | M2[Al4Si14O36] · 15H2O | |
| Fabrièsite | Na3Al3Si3O12 · 2H2O | Orth. mm2 : Pmm2 |
| Faujasite Subgroup | M3.5[Al7Si17O48] · 32H2O | |
| Ferrierite Subgroup | Name used for unanalysed specimens that could be either ferrierite-K, ferrierite-Mg, ... | |
| Ferrochiavennite | Ca1-2Fe[(Si,Al,Be)5Be2O13(OH)2] · 2H2O | Mon. 2/m : P21/b |
| Flörkeite | (K3Ca2Na)[Al8Si8O32] · 12H2O | Tric. 1 : P1 |
| Garronite Subgroup | ||
| Gaultite | Na4Zn2Si7O18 · 5H2O | Orth. mm2 : Fdd2 |
| Gismondine Subgroup | Zeolite Group. | |
| Gmelinite Subgroup | In 1997, gmelinite was split into Gmelinite-Ca, Gmelinite-Na and Gmelinite-K. | |
| Gobbinsite | Na5(Si11Al5)O32 · 11H2O | Orth. mmm(2/m2/m2/m) : Pnma |
| Goosecreekite | Ca[Al2Si6O16] · 5H2O | Mon. 2 : P21 |
| Gottardiite | Na3Mg3Ca5Al19Si117O272 · 93H2O | Orth. mmm(2/m2/m2/m) : Cmca |
| Heulandite Subgroup | (Na/Ca/K)5-6[Al8-9 Si27-28 O72] · nH2O | |
| Hsianghualite | Ca3Li2(Be3Si3O12)F2 | Iso. 23 : I213 |
| Kalborsite | K6Al4BSi6O20(OH)4Cl | Tet. 42m : P421c |
| Kirchhoffite | Cs(BSi2O6) | Tet. 4/mmm(4/m2/m2/m) : I41/acd |
| Laumontite | CaAl2Si4O12 · 4H2O | Mon. 2/m : B2/m |
| Leucite | K(AlSi2O6) | Tet. 4/m : I41/a |
| Limousinite | BaCa[Be4P4O16] · 6H2O | Mon. 2/m : P21/b |
| Lithosite | K6Al4Si8O25 · 2H2O | Mon. |
| Loomisite | Ba[Be2P2O8] · H2O | Mon. m |
| Lovdarite | K2Na6Be4Si14O36 · 9H2O | Orth. mm2 |
| Maricopaite | Pb7Ca2(Si,Al)48O100 · 32H2O | Orth. |
| Martinandresite | Ba2(Al4Si12O32) · 10H2O | Orth. mmm(2/m2/m2/m) : Pmmn |
| Mazzite Subgroup | Zeolite Group. | |
| Meierite | Ba44Si66Al30O192Cl25(OH)33 | Iso. m3m(4/m32/m) : Im3m |
| Merlinoite | K5Ca2(Si23Al9)O64 · 24H2O | Orth. mmm(2/m2/m2/m) : Immm |
| Montesommaite | (K,Na)9Al9Si23O64 · 10H2O | Orth. mm2 : Fdd2 |
| Mordenite | (Na2,Ca,K2)4(Al8Si40)O96 · 28H2O | Orth. |
| Mountainite | KNa2Ca2[Si8O19(OH)] · 6H2O | Mon. 2/m : P2/b |
| Mutinaite | Na3Ca4Si85Al11O192 · 60H2O | Orth. mmm(2/m2/m2/m) : Pnma |
| Nabesite | Na2BeSi4O10 · 4H2O | Orth. 222 : P212121 |
| Natrolite Subgroup | A subgroup of the Zeolite Group. | |
| Pahasapaite | Li8(Ca,Li,K)10.5Be24(PO4)24 · 38H2O | Iso. 23 : I23 |
| Parthéite | Ca2(Si4Al4) O15 (OH)2 · 4H2O | Mon. 2/m : B2/b |
| Paulingite Subgroup | Paulingite was originally described in 1960. | |
| Perlialite | K9Na(Ca,Sr)[Al2Si4O12]6 · 15H2O | Hex. 6/mmm(6/m2/m2/m) : P6/mmm |
| Phillipsite Subgroup | (Ca0.5,K,Na,Ba0.5)4-7[Al4-7Si12-9O32] . 12H2O | |
| Pollucite | (Cs,Na)2(Al2Si4O12) · 2H2O | Iso. m3m(4/m32/m) : Ia3d |
| Roggianite | Ca2Be(OH)2Al2Si4O13 · 2.5H2O | Tet. 4/mmm(4/m2/m2/m) : I4/mcm |
| Rongibbsite | Pb2(Si4Al)O11(OH) | Mon. 2/m : B2/m |
| Stilbite Subgroup | M6-7[Al8-9Si27-28O72] · nH2O | |
| Terranovaite | (Na,Ca)8(Si68Al12)O160 · 29H2O | Orth. |
| Thomsonite Subgroup | The large majority of "thomsonite" is thomsonite-Ca. | |
| Thornasite | Na12Th4+3(Si8O19)4 · 18H2O | Trig. 3m : R3m |
| Tschernichite | (Ca,Na2)[Al2Si4O12] · 4-8H2O | Tet. 4/mmm(4/m2/m2/m) : P4/mmm |
| Tschörtnerite | Ca4(Ca,Sr,K,Ba)3Cu3[Al3Si3O12]4(OH)8 · nH2O | Iso. m3m(4/m32/m) : Fm3m |
| 'UM1996-38-SiO:AlCaHNa' | Na-Ca-Al-Si-O-H | |
| 'UM1999-33-SiO:AlHKNa' | K7Na5Al12Si20O64 · 24H2O | |
| 'UM2002-40-SiO:AlCaHKMgNa' | (Mg,Ca,Na,K)7.5(Al12.8Si51.2)O128 · 65H2O | Tet. 422 : P4122 |
| 'Unnamed (Ca analogue of Merlinoite)' | (Ca,K,Na)5(Ca,Ba)2Al9Si23O64 · 23H2O ? | |
| Wairakite | Ca(Al2Si4O12) · 2H2O | Mon. 2/m : B2/m |
| Weinebeneite | CaBe3(PO4)2(OH)2 · 4H2O | Mon. m : Bb |
| Wenkite | (Ba,K)4(Ca,Na)6[(Si,Al)20O39(OH)2](SO4)3 · 0.5H2O | Hex. 6m2 : P62m |
| Wilancookite | (Ba5Li2◻)Ba6Be24P24O96 · 26H2O | Iso. 23 : I23 |
| Willhendersonite | KCa[Al3Si3O12] · 5H2O | Tric. 1 : P1 |
| Yugawaralite | CaAl2Si6O16 · 4H2O | Mon. m : Pb |
Common Associates
Associations Based on Photo Data:
| 101 photos of Offretite associated with Chabazite | |
| 80 photos of Offretite associated with Phillipsite Subgroup | (Ca0.5,K,Na,Ba0.5)4-7[Al4-7Si12-9O32] . 12H2O |
| 60 photos of Offretite associated with Smectite Group | A0.3D2-3[T4O10]Z2 · nH2O |
| 51 photos of Offretite associated with Faujasite Subgroup | M3.5[Al7Si17O48] · 32H2O |
| 48 photos of Offretite associated with Lévyne-Ca | (Ca,Na2,K2)[Al2Si4O12] · 6H2O |
| 47 photos of Offretite associated with Lévyne | |
| 37 photos of Offretite associated with Montmorillonite | (Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2 · nH2O |
| 26 photos of Offretite associated with 'Opal-AN' | SiO2 · nH2O |
| 24 photos of Offretite associated with Chabazite-K | (K2,Ca,Na2,Sr,Mg)2[Al2Si4O12]2 · 12H2O |
| 22 photos of Offretite associated with Erionite-Ca | (Ca,K2,Na2)2[Al4Si14O36] · 15H2O |
Related Minerals - Strunz-mindat Grouping
| 9.GD.05 | Gmelinite-Ca | Ca2(Si8Al4)O24 · 11H2O |
| 9.GD.05 | Gmelinite-K | K4(Si8Al4O24) · 11H2O |
| 9.GD.05 | Gmelinite-Na | Na4(Si8Al4)O24 · 11H2O |
| 9.GD.10 | Chabazite-Mg | (Mg0.7K0.5Ca0.5Na0.1)[Al3Si9O24] · 10H2O |
| 9.GD.10 | Willhendersonite | KCa[Al3Si3O12] · 5H2O |
| 9.GD.10 | Chabazite-Ca | (Ca,K2,Na2)2[Al2Si4O12]2 · 12H2O |
| 9.GD.10 | Chabazite-K | (K2,Ca,Na2,Sr,Mg)2[Al2Si4O12]2 · 12H2O |
| 9.GD.10 | Chabazite-Na | (Na2,K2,Ca,Sr,Mg)2[Al2Si4O12]2 · 12H2O |
| 9.GD.10 | Chabazite-Sr | Sr2[Al2Si4O12]2 · 12H2O |
| 9.GD.15 | Lévyne-Ca | (Ca,Na2,K2)[Al2Si4O12] · 6H2O |
| 9.GD.15 | Lévyne-Na | (Na2,Ca,K2)[Al2Si4O12] · 6H2O |
| 9.GD.20 | Erionite-Ca | (Ca,K2,Na2)2[Al4Si14O36] · 15H2O |
| 9.GD.20 | Erionite-K | (K2,Ca,Na2)2[Al4Si14O36] · 15H2O |
| 9.GD.20 | Erionite-Na | (Na2,K2,Ca)2[Al4Si14O36] · 15H2O |
| 9.GD.20 | Bellbergite | (K,Ba,Sr)2Sr2Ca2(Ca,Na)4[Al3Si3O12]6 · 30H2O |
| 9.GD.25 | Wenkite | (Ba,K)4(Ca,Na)6[(Si,Al)20O39(OH)2](SO4)3 · 0.5H2O |
| 9.GD.30 | Faujasite-Ca | (Ca,Na2,Mg)3.5[Al7Si17O48] · 32H2O |
| 9.GD.30 | Faujasite-Mg | (Mg,Na2,Ca)3.5[Al7Si17O48] · 32H2O |
| 9.GD.30 | Faujasite-Na | (Na2,Ca,Mg)3.5[Al7Si17O48] · 32H2O |
| 9.GD.35 | Maricopaite | Pb7Ca2(Si,Al)48O100 · 32H2O |
| 9.GD.35 | Mordenite | (Na2,Ca,K2)4(Al8Si40)O96 · 28H2O |
| 9.GD.40 | Dachiardite-K | K4(Si20Al4O48) · 13H2O |
| 9.GD.40 | Dachiardite-Ca | (Ca,Na2,K2)5Al10Si38O96 · 25H2O |
| 9.GD.40 | Dachiardite-Na | (Na2,Ca,K2)5Al10Si38O96 · 25H2O |
| 9.GD.45 | Epistilbite | CaAl2Si6O16 · 5H2O |
| 9.GD.50 | Ferrierite-K | (K,Na)5(Si31Al5)O72 · 18H2O |
| 9.GD.50 | Ferrierite-Mg | [Mg2(K,Na)2Ca0.5](Si29Al7)O72 · 18H2O |
| 9.GD.50 | Ferrierite-Na | (Na,K)5(Si31Al5)O72 · 18H2O |
| 9.GD.50 | Ferrierite-NH4 | (NH4,Mg0.5)5(Al5Si31O72) · 22H2O |
| 9.GD.55 | Bikitaite | LiAlSi2O6 · H2O |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 0.0000% | 0 | α, β, γ |
| Thorium (Th) | 0.0000% | 0 | α, β, γ |
| Potassium (K) | 2.6970% | 836 | β, γ |
For comparison:
- Banana: ~15 Bq per fruit
- Granite: 1,000–3,000 Bq/kg
- EU exemption limit: 10,000 Bq/kg
Note: Risk is shown relative to daily recommended maximum exposure to non-background radiation of 1000 µSv/year. Note that natural background radiation averages around 2400 µSv/year so in reality these risks are probably extremely overstated! With infrequent handling and safe storage natural radioactive minerals do not usually pose much risk.
Interactive Simulator:
Note: The mass selector refers to the mass of radioactive mineral present, not the full specimen, also be aware that the matrix may also be radioactive, possibly more radioactive than this mineral!
Activity: –
| Distance | Dose rate | Risk |
|---|---|---|
| 1 cm | ||
| 10 cm | ||
| 1 m |
The external dose rate (D) from a radioactive mineral is estimated by summing the gamma radiation contributions from its Uranium, Thorium, and Potassium content, disregarding daughter-product which may have a significant effect in some cases (eg 'pitchblende'). This involves multiplying the activity (A, in Bq) of each element by its specific gamma ray constant (Γ), which accounts for its unique gamma emissions. The total unshielded dose at 1 cm is then scaled by the square of the distance (r, in cm) and multiplied by a shielding factor (μshield). This calculation provides a 'worst-case' or 'maximum risk' estimate because it assumes the sample is a point source and entirely neglects any self-shielding where radiation is absorbed within the mineral itself, meaning actual doses will typically be lower. The resulting dose rate (D) is expressed in microsieverts per hour (μSv/h).
D = ((AU × ΓU) + (ATh × ΓTh) + (AK × ΓK)) / r2 × μshield
Other Information
Notes:
In a flame it whitens and melts into a white enamel without bubbling. Heated in a test tube, it releases water. Attacked incompletely and with difficulty by acids (cold or hot).
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 Offretite
mindat.org URL:
https://www.mindat.org/min-2960.html
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References for Offretite
Reference List:
Gonnard, Ferdinand (1891) Sur l'Offrétite, nouvelle espèce minérale. Bulletin de la Société Française de Minéralogie, 14 (2) 58-60 doi:10.3406/bulmi.1891.2205
Sheppard, Richard A., Gude, Arthur J., 3rd, (1969) Chemical composition and physical properties of the related zeolites offretite and erionite. American Mineralogist, 54 (5-6) 875-886
Gualtieri, A., Artioli, G., Passaglia, E., Bigi, S., Viani, A., Hanson, J. C. (1998) Crystal structure-crystal chemistry relationships in the zeolites erionite and offretite. American Mineralogist, 83 (5) 590-606 doi:10.2138/am-1998-5-619
Passaglia, E., Artioli, G., Gualtieri, A. (1998) Crystal chemistry of the zeolites erionite and offretite. American Mineralogist, 83 (5-6) 577-589
Dogan, A. Umran, Dogan, Meral (2008) Re-evaluation and re-classification of erionite series minerals. Environmental Geochemistry and Health, 30. 355-366 doi:10.1007/s10653-008-9163-z
Saini-Eidukat, B., Triplett, J. W. (2014) Erionite and offretite from the Killdeer Mountains, Dunn County, North Dakota, U.S.A. American Mineralogist, 99 (1) 8-15 doi:10.2138/am.2014.4567
Kol’tsova, T. N. (2016) Solid solutions of offretite, direnzoite, and ferrierite. Inorganic Materials, 52 (8) 743-754 doi:10.1134/s0020168516080112
Mattioli, Michele, Giordani, Matteo, Arcangeli, Pierluca, Valentini, Laura, Boscardin, Matteo, Pacella, Alessandro, Ballirano, Paolo (2018) Prismatic to Asbestiform Offretite from Northern Italy: Occurrence, Morphology and Crystal-Chemistry of a New Potentially Hazardous Zeolite. Minerals, 8 (2) 69 doi:10.3390/min8020069
Localities for Offretite
Showing 198 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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Roßberg Quarry, Roßdorf, Darmstadt-Dieburg, Darmstadt, Hesse, Germany