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Pictures (77 Images total)

Offretit
Views (Image: 1240648157): 3331, Rating: 9.57
Offretit

Größe: 1,91 mm; Fundort: Fittà, Soave, Verona, Venetien (Veneto), Italien
Copyright: Matteo Chinellato
Contribution: Hg 2009-04-25
Locality: Fittà / Soave / Verona, Provinz / Venetien (Veneto), Region / Italien
Offretit
Views (Image: 1231095619): 2798
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Größe: 2 mm; Fundort: Berg Scagno (Monte Scagno), Case Nori, Montorso Vicentino, Vicenza, Venetien (Veneto), Italien
Copyright: Matteo Chinellato
Contribution: Hg 2009-01-04
Locality: Berg Scagno (Monte Scagno) / Case Nori / Montorso Vicentino / Vicenza, Provinz / Venetien (Veneto), Region / Italien
Offretit
Views (Image: 1630695789): 229
Offretit

Herbstein, Vogelsberg, Hessen, Bildbreite 1,3mm
Collection: Karl-Heinz M.
Copyright: Karl-Heinz M.
Contribution: khm 2021-09-03
Locality: Herbstein / Vogelsbergkreis / Gießen, Bezirk / Hessen / Deutschland
Offretit
Views (Image: 1635772543): 527
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Offretit als winzige Kugeln mit ca 0,5 mm Größe, in deren Mitte jeweils ein großer aggregierter Kristall zu sehen ist, vom Limberg, Kaiserstuhl, BB ca 2 mm
Collection: Dieter Strangfeld
Copyright: Dieter Strangfeld
Contribution: Dieter Strangfeld 2021-11-01
Locality: Limberg / Sasbach am Kaiserstuhl / Emmendingen, Landkreis / Freiburg, Bezirk / Baden-Württemberg / Deutschland
Offretit
Views (Image: 1630695822): 236
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Herbstein, Vogelsberg, Hessen, Bildbreite 1,3mm
Collection: Karl-Heinz M.
Copyright: Karl-Heinz M.
Contribution: khm 2021-09-03
Locality: Herbstein / Vogelsbergkreis / Gießen, Bezirk / Hessen / Deutschland
Offretit
Views (Image: 1241771885): 3064, Rating: 9.14
Offretit

Größe: 1,31 mm; Fundort: Berg Scagno (Monte Scagno), Case Nori, Montorso Vicentino, Vicenza, Venetien (Veneto), Italien
Copyright: Matteo Chinellato
Contribution: Hg 2009-05-08
Locality: Berg Scagno (Monte Scagno) / Case Nori / Montorso Vicentino / Vicenza, Provinz / Venetien (Veneto), Region / Italien

Collectors Summary

Color farblos, weiß
Streak color weiß
Lustre Glasglanz
Hardness (Mohs) 4
Fracture Uneben, spröde
Solubility +++ Säuren
Crystal System hexagonal, P6m2
Morphology Hexagonale, prismatische, radialstrahlige, kugelige Aggregate

Chemism

Chem­ical formula

KCaMg(Si13Al5)O36·15H2O

Chem­ical com­po­si­tion

Aluminium, Calcium, Magnesium, Silicium, Kalium, Sauerstoff, Wasserstoff

Unit weight: 1449.710691 u; Number of atoms in the formula: 102

Info

Empirical formula:

KCaMg(Si13Al5)O36·15H2O

Element

Symbol

Weight%

Atoms

Atoms%

Atom weight (u)

Sum weight (u)
Hydrogen

H

2.09

30

29.41

1.0079470

30.2384100
Oxygen

O

56.29

51

50.00

15.9994300

815.9709300
Magnesium

Mg

1.68

1

0.98

24.3050600

24.3050600
Aluminium

Al

9.31

5

4.90

26.9815382

134.9076910
Silicon

Si

25.19

13

12.75

28.0855300

365.1118900
Potassium

K

2.70

1

0.98

39.0983100

39.0983100
Calcium

Ca

2.76

1

0.98

40.0784000

40.0784000

Anal­y­sis wt%

SiO2 : 53.00, Al2O3 : 18.10, MgO : 2.00, CaO : 4.10, K2O : 3.60, H2O : 18.80 (Ref: American Mineralogist 69)

Strunz 9th edi­tion incl. updates

9.GD.25

9: Silikate (Germanate)
G: Gerüstsilikate (Tektosilikate) mit zeolithischem H2O; Familie der Zeolithe
D: Ketten von fünfer-Ringen
25:Offrétit-Gruppe

Lapis Clas­sifica­tion

VIII/J.26-070

VIII: SILIKATE
J: Gerüstsilikate (mit Zeolithen)
26: Zeolith-Gruppe; Würfelzeolithe

Clas­sifica­tion by Hölzel

9.FL.200

9: SILICATES
F: Tektosilicates
L: Zeolites with 6-Rings

Dana 8th edi­tion

77.01.02.04

77: Tektosilicates Tectosilicate Zeolite group
01: Tektosilicates Tectosilicate Zeolite group true zeolites
02: Chabazite and related species

IMA sta­tus

Anerkannt von der CNMNC

Min­eral sta­tus

anerkanntes Mineral

IMA Classification

IMA Clas­sifica­tion

 Zeolite group  ⇒ OFF zeolite structure group

Optical Properties

Color

farblos, weiß

Streak color

weiß

Diaphane­ity (Trans­parency)

transparent bis durchscheinend

Lus­tre

Glasglanz

max. Birefrin­gence

0.003
Birefringence chart\! Offretite title=Birefringence chart Offretite

Michel-Levy Color Chart viewed according to the maximum birefringence (at 30μm). Mineral color is not taken into account. Click on the image to enlarge or change thickness.

RI value α / ω / n

1.489

RI value γ / ε

1.486

Ri mean

1.488

2V angle

Uniaxial (-)

Crystallography

Crystal Sys­tem

hexagonal

Class (H-M)

6m2

Space Group number

187

Space Group

P6m2

Cell param­e­ters a (Å)

13.306

Cell param­e­ters b (Å)

-

Cell param­e­ters c (Å)

7.585

Cell param­e­ters a/b or c/a

0.570

Cell param­e­ters c/b

-

Cell param­e­ters α

90°

Cell param­e­ters β

90°

Cell param­e­ters γ

120°

Z

1

Volumne (ų)

1163.004

X-Ray Pow­der Diffrac­tion

11.50(100),
6.64(20),
5.76(30),
4.352(60),
3.837(40),
3.322(20),
2.880(60),
2.510(20)
XRD chart Offretite

Calculated from d-spacing and intensity at 0.1541838 nm (Cu)

Morphol­ogy

Hexagonale, prismatische, radialstrahlige, kugelige Aggregate

Crystals 3D

Open larger view

Crystal Structure 3D

Open larger view

Physical Properties

Hard­ness (Mohs)

4

VHN (Hard­ness Vick­ers)

190 (ungefähre Angabe abgeleitet aus der Mohshärte)

Density (g/cm³)

2.13

2.07 ( ρ calc. Mineralienatlas )

Frac­ture

Uneben, spröde

Insta­bil­ity

+++ Säuren

(Co-)Type locality

(Co-)Type locality

Frankreich/Auvergne-Rhône-Alpes, Region/Loire, Département/Montbrison, Arrondissement/Montbrison/Mont Semiol

Preface

Author (Name, Year)

Gonnard, 1890

References

Canadian Mineralogist 35 (1997), 1571

IMA group assignments

 
Zeolite group
 
 
 

 
 
OFF zeolite structure group
 
 
 

 
 
 
Offretite
KCaMg(Si13Al5)O36·15H2O
hexagonal
P6m2

 
 
 
Wenkite
Ba4Ca6(Si,Al)20O41(OH)2(SO4)3·H2O
hexagonal
P62m

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Actuality: 21. Jun 2022 - 18:25:16

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Оффретит

Alternative Name

Offrtite

Offrétite

CNMNC symbol

Symbol

Off

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