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Almarudite

Big Photo

Caspar quarry, Ettringer Bellerberg Mt. (Bellberg Mt.; Bellenberg Mt.; Billenberg Mt.; Boilenberg Mt.), Bellerberg volcano, Ettringen, Mayen, Eifel Mts, Rhineland-Palatinate, Germany
© Stephan Wolfsried

Show Almarudite Photos (3)
Formula:
K([],Na)
 
2
(Mn
2+
 
,Fe
2+
 
,Mg)
 
2
(Be,Al)
 
3
[Si
 
12
O
 
30
]
System:HexagonalColour:yellow to orange
Hardness:6
Name:For the University of Vienna, Austria (in latin: ALma MAter RUDolphina)


Osumilite Group.
Calcium- and water-free analogue of milarite.

Can be distinguished from its Mg analogue friedrichbeckeite and yellowish roedderite only by quantitative chemical analysis.

Classification of Almarudite

IMA status:Approved 2002
Strunz 8th edition ID:8/E.22-22
Nickel-Strunz 10th (pending) edition ID:9.CM.05

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

Type Locality:Caspar quarry, Ettringer Bellerberg Mt. (Bellberg Mt.; Bellenberg Mt.; Billenberg Mt.; Boilenberg Mt.), Bellerberg volcano, Ettringen, Mayen, Eifel Mts, Rhineland-Palatinate, Germany
General Appearance of Type Material:tabular crystals to 1.5 mm across
Year of Discovery:1982
Geological Setting of type material:in vugs of siliceous xenolites in leucite-rich lava slags
Associated Minerals at type locality:
TridymiteSillimaniteSanidineQuartzHematite
Clinopyroxene SubgroupBrauniteAmphibole Group

Physical Properties of Almarudite

Lustre:Vitreous
Diaphaneity (Transparency):Transparent, Translucent
Colour:yellow to orange
Streak:pale orange
Hardness (Mohs):6
Tenacity:Brittle
Cleavage:None Observed
Fracture:Irregular/Uneven
Density (measured):2.71 g/cm3

Crystallography of Almarudite

Crystal System:Hexagonal
Class (H-M):6/mmm (6/m 2/m 2/m) - Dihexagonal Dipyramidal
Space Group:P6/mmm {P6m 2/m 2/m}
Cell Parameters:a = 9.99Å, c = 14.09Å
Ratio:a:c = 1 : 1.41
Unit Cell Volume:V 1,217.79 ų (Calculated from Unit Cell)
Morphology:{0001}, {10_10}, {10_12}, {11_20}
X-Ray Powder Diffraction:
d-spacingIntensity
4.07 (80)
3.18 (90)

Chemical Properties of Almarudite

Formula:
K([],Na)
 
2
(Mn
2+
 
,Fe
2+
 
,Mg)
 
2
(Be,Al)
 
3
[Si
 
12
O
 
30
]
Essential elements:Be, K, Mn, O, Si
All elements listed in formula:Al, Be, Fe, K, Mg, Mn, Na, O, Si

Relationship of Almarudite to other Species

Member of Group:
Osumilite Group:
Related Minerals - Nickel-Strunz Grouping):

- +
9.CM.05Armenite
BaCa
 
2
Al
 
6
Si
 
9
O
 
30
·2H
 
2
O
9.CM.05Brannockite
(K,Na)Li
 
3
Sn
 
2
Si
 
12
O
 
30
9.CM.05Chayesite
K(Mg,Fe)
 
4
FeSi
 
12
O
 
30
9.CM.05Darapiosite
KNa
 
2
Li(Mn,Zn)
 
2
ZrSi
 
12
O
 
30
9.CM.05Eifelite
KNa
 
3
Mg
 
4
Si
 
12
O
 
30
9.CM.05Merrihueite
(K,Na)
 
2
(Fe,Mg)
 
5
Si
 
12
O
 
30
9.CM.05Milarite
K
 
2
Ca
 
4
Al
 
2
Be
 
4
Si
 
24
O
 
60
·H
 
2
O
9.CM.05Osumilite-(Mg)
(K,Na)(Mg,Fe)
 
2
(Al,Fe)
 
3
(Si,Al)
 
12
O
 
30
·H
 
2
O
9.CM.05Osumilite
(K,Na)(Fe
2+
 
,Mg)
 
2
(Al,Fe
3+
 
)
 
3
(Si,Al)
 
12
O
 
30
9.CM.05Poudretteite
KNa
 
2
B
 
3
Si
 
12
O
 
30
9.CM.05Roedderite
(Na,K)
 
2
(Mg,Fe)
 
5
Si
 
12
O
 
30
9.CM.05Sogdianite
(K,Na)
 
2
(Li,Fe)
 
3
(Zr,Ti,Fe)Si
 
12
O
 
30
9.CM.05Sugilite
KNa
 
2
(Fe,Mn,Al)
 
2
Li
 
3
Si
 
12
O
 
30
9.CM.05Yagiite
(Na,K)
 
3
Mg
 
4
(Al,Mg)
 
6
(Si,Al)
 
24
O
 
60
9.CM.05Berezanskite
KLi
 
3
Ti
 
2
Si
 
12
O
 
30
9.CM.05Dusmatovite
K(K,Na,[ ])(Mn
2+
 
,Y,Zr)
 
2
(Zn,Li)
 
3
Si
 
12
O
 
30
9.CM.05Shibkovite
K(Ca,Mn,Na)
 
2
(K
 
2-x
,□
 
x
)
 
2
Zn
 
3
Si
 
12
O
 
30
9.CM.05Trattnerite
([],K)(Mg, Fe
2+
 
)
 
3
Fe
3+
2
[Si
 
12
O
 
30
]
9.CM.05Oftedalite
(Sc,Ca,Mn
2+
 
)
 
2
K[(Be,Al)
 
3
Si
 
12
O
 
30
]
9.CM.10Faizievite
K
 
2
Na(Ca
 
6
Na)Ti
 
4
Li
 
6
[F
 
2
|Si
 
24
O
 
66
]

Other Names for Almarudite

Synonyms:
IMA2002-048
Other Languages:
German:Almarudit

Other Information

Fluorescence in UV light:none
Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Almarudite

Reference List:Mihajlovic, T., Lengauer, C.L., Ntaflos, Th., Kolitsch, U., Tillmanns, E. (2004): Two new minerals, rondorfite, Ca8Mg[SiO4]4Cl2, and almarudite, K(,Na,)2(Mn,Fe,Mg)2(Be,Al)3[Si12O30], and a study of iron-rich wadalite, Ca12[(Al8Si4Fe2)O32]Cl6, from the Bellerberg volcano, Eifel, Germany, N. Jb. Miner. Abh. 179, 265-294.

Lapis 29(3), 39 (2004)

Rondorf, A. & Rondorf, E. (2008): Almarudit vom Bellerberg/Eifel. Mineralien-Welt 19 (5), 4.

Internet Links for Almarudite

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    Localities for Almarudite

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