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Pictures (77 Images total)

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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
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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: 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
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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
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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

Preface

Author (Name, Year)

Gonnard, 1890

References

Canadian Mineralogist 35 (1997), 1571

IMA group assignments



 
 
 
KCaMg(Si13Al5)O36·15H2O
hexagonal
P6m2

 
 
 
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

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Symbol

Off

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