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Almeidaite (IMA 2013-020)

Pictures (2 Images total)

Almeidaite
Views (File:
1441429139
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Almeidaite
Locality: Unnamed deposit, Novo Horizonte, Bahia, Brazil; Dimensions: 2 cm x 1.5 cm x 0.7 cm; A very recently discovered new species that has been approved by the IMA this year. The sample, a flattened crystal with very well defined faces and edges, gray color with brownish shades and a good luster, was personally collected by Luiz Menezes, first author of the article that describes the species. This specimen was published on the Mineralogical Record´s web page, in the ‘What’s New in the Mineral World?’ section, report #35, August 14, 2013 edition. Novo Horizonte, Bahía, Brazil; Found in 04/2013; Specimen size: 2 × 1.5 × 0.7 cm = 0.8” × 0.6” × 0.3”
Copyright: Fabre Minerals; Contribution: Stefan
Location: Brasilien/Nordosten (Região Nordeste)/Bahia/Novo Horizonte/Unbenanntes Vorkommen
Mineral: Almeidaite
Image: 1441429139
License: Usage for Mineralienatlas project only
Almeidaite

Locality: Unnamed deposit, Novo Horizonte, Bahia, Brazil; Dimensions: 2 cm x 1.5 cm x 0.7 cm; A very recently discovered new species that has been approved by the IMA this year. The sample, a flatt...

Copyright: Fabre Minerals
Contribution: Stefan 2015-09-05
Locality: Unbenanntes Vorkommen / Novo Horizonte / Bahia / Nordosten (Região Nordeste) / Brasilien
Almeidait
Views (File:
1484582431
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Almeidait
Schwarzbrauner Kristall von Almeidait, 12 x 11 x 4 mm. Fundort: Novo Horizonte, Bahia, Brasilien
Copyright: Yi Sun; Contribution: sun-mineral
Collection: Yi Sun
Location: Brasilien/Nordosten (Região Nordeste)/Bahia/Novo Horizonte
Mineral: Almeidaite
Image: 1484582431
License: Usage for Mineralienatlas project only
Almeidait

Schwarzbrauner Kristall von Almeidait, 12 x 11 x 4 mm. Fundort: Novo Horizonte, Bahia, Brasilien

Collection: Yi Sun
Copyright: Yi Sun
Contribution: sun-mineral 2017-01-16
Locality: Novo Horizonte / Bahia / Nordosten (Região Nordeste) / Brasilien

Collectors Summary

Color schwarz
Streak color braun
Lustre Halbmetallglanz
Crystal System trigonal, R3
Morphology einzelne abgeflachte Kristalle; abgeflacht auf [0001]; Größe bis 30x30x6mm; dominiert vom Basispinakoid {0001} die von verschiedenen, meist steilen, Rhomboedern und dem hexagonalem Prisma {1120} begrenzt wird. Die meisten der Kristalle sind mehrfach verzwillingt, mit nicht-ebenen Berührungsflächen, die annähernd parallel zu der c-Achse sind.

Additional information / Summary

Almeidaite ist ein Mitglied der Crichtonit-Gruppe mit Pb dominant in der A-Stelle (mit 12-facher Koordination) und Zn dominant auf der T-Seite (bei 4-fach-Koordination). Es ist eine Zn Analog von Senait und ein Pb Analog von Landauit.

Chemism

Chemical formula

PbZn2(Mn,Y)(Ti,Fe3+)18O36(OH,O)2

Empirical formula (analysis)

(Pb0.59Sr0.12Ca0.04La0.03)Σ0.78(Mn0.54Y0.46)Σ1.00Zn1.43(Ti13.02Fe3+4.98)Σ18.00(Fe3+0.32Mn0.15)Σ0.47 [O37.18(OH)0.82]Σ38.00

Additional chem. information

Crichtonit-Gruppe

Chemical composition

Blei, Eisen, Mangan, Titan, Yttrium, Zink, Sauerstoff, Wasserstoff

Unit weight: 1838.892168491 u; Number of atoms in the formula: 60.5

Info

Empirical formula:

(Pb0.59Sr0.12Ca0.04La0.03)(Mn0.54Y0.46)Zn1.43(Ti13.02Fe4.98)(Fe0.32Mn0.15)[O37.18(OH)0.82]

Element

Symbol

Weight%

Atoms

Atoms%

Atom weight (u)

Sum weight (u)

Hydrogen

H

0.04

0.82

1.36

1.0079470

0.8265165

Oxygen

O

33.06

38

62.81

15.9994300

607.9783400

Calcium

Ca

0.09

0.04

0.07

40.0784000

1.6031360

Titanium

Ti

33.89

13.02

21.52

47.8671000

623.2296420

Manganese

Mn

2.06

0.69

1.14

54.9380499

37.9072544

Iron

Fe

16.10

5.3

8.76

55.8452000

295.9795600

Zinc

Zn

5.09

1.43

2.36

65.4094000

93.5354420

Strontium

Sr

0.57

0.12

0.20

87.6210000

10.5145200

Yttrium

Y

2.22

0.46

0.76

88.9058520

40.8966919

Lanthanum

La

0.23

0.03

0.05

138.9055200

4.1671656

Lead

Pb

6.65

0.59

0.98

207.2100000

122.2539000

Strunz 9th edition incl. updates

4.CC.40

4: Oxide, Hydroxide (Oxide, Hydroxide, V[5,6]-Vanadate, Arsenite, Antimonite, Bismutite, Sulfite, Selenite, Tellurite, Iodate)
C: Metall: Sauerstoff = 2: 3,3: 5, und vergleichbare
C: Mit großen und mittelgroßen Kationen
40:Crichtonit-Gruppe

Lapis Classification

IV/C.09-055

IV: OXIDE
C: Oxide mit Verhältnis Metall : Sauerstoff = 2:3 (M2O3 und verwandte Verbindungen)
9: Crichtonit-Gruppe

IMA status

anerkannt - CNMNC Newsletter No. 16, August 2013

Mineral status

anerkanntes Mineral

IMA Classification

IMA Classification

Crichtonite Group

Optical Properties

Color

schwarz

Streak color

braun

Diaphaneity (Transparency)

opak

Lustre

Halbmetallglanz

Reflectivity: (Lambda nm) ↓, ↑, Ø

(470) 12.78, 15.39, 14.09
(546) 12.86, 15.43, 14.15
(589) 12.91, 15.55, 14.23
(650) 13.04, 15.75, 14.40

Reflection chart Almeidaite

Reflectivity Ø

14.22

Crystallography

Crystal System

trigonal

Class (H-M)

3

Space Group number

148

Space Group

R3

Cell parameters a (Å)

10.4359

Cell parameters b (Å)

-

Cell parameters c (Å)

21.0471

Cell parameters a/b or c/a

2.017

Cell parameters c/b

-

Z

3

Volume (ų)

1985.101

X-Ray Powder Diffraction

3.436(48), 3.074(50), 3.023(50), 2.907(100), 2.781(44), 2.492(55), 2.157(55), 1.615(50)

XRD chart Almeidaite

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

Morphology

einzelne abgeflachte Kristalle; abgeflacht auf [0001]; Größe bis 30x30x6mm; dominiert vom Basispinakoid {0001} die von verschiedenen, meist steilen, Rhomboedern und dem hexagonalem Prisma {1120} begrenzt wird. Die meisten der Kristalle sind mehrfach verzwillingt, mit nicht-ebenen Berührungsflächen, die annähernd parallel zu der c-Achse sind.

Crystals 3D

Open larger view

Crystal Structure 3D

Open larger view

Physical Properties

Density (g/cm³)

4.61 (berechnet)

4.614 ( ρ calc. Mineralienatlas )

(Co-)Type locality

(Co-)Type locality

Type material

Museu de Geociências, Instituto de Geociências, Universidade de São Paulo, São Paulo, Brazilien

Collection number of type material

DR744

Preface

Name from

Professor Fernando Flávio Marques de Almeida (1916–2013)

Author (Name, Year)

Luiz A.D. Menezes Filho, Nikita V. Chukanov, Ramiza K. Rastsvetaeva, Sergey M. Aksenov, Igor V. Pekov, Mário L.S.C. Chaves, Ricardo Scholz, Daniel Atencio, Paulo R.G. Brandão, Antônio W. Romano, Luiz C.A. de Oliveira, José D. Ardisson, Klaus Krambrock, Ro

References

Luiz A.D. Menezes Filho, L.A.D., Chukanov, N.V., Rastsvetaeva, R.K., Aksenov, S.M., Pekov, I.V., Chaves, M.L.S.C., Scholz, R., Atencio, D., Brandão, P.R.G., Romano, A.W., de Oliveira, L.C.A., Ardisson, J.D., Krambrock, K., Moreira, R.L., Guimarães, F.S., Persiano, A.C. and Richards, R.P. (2013) Almeidaite, IMA 2013-020. CNMNC Newsletter No. 16, 2013, page 2705; Mineralogical Magazine, 77, 2695-2709.

Menezes Filho, L.A.D., Chukanov, N.V., Rastsvetaeva, R.K., Aksenov, S.M., Pekov, I.V., Chaves, M.L.S.C., Scholz, R., Atencio, D., Brandão, P.R.G., Romano, A.W., de Oliveira, L.C.A., Ardisson, J.D., Krambrock, K., Moreira, R.L., Guimarães, F.S., Persiano, A.C., Richards, R.P.(2015): Almeidaite, Pb(Mn,Y)Zn2(Ti,Fe3+)18O36(O,OH)2, a new crichtonite-group mineral, from Novo Horizonte, Bahia, Brazil. Mineralogical Magazine, 79, (in press).

IMA group assignments

Other languages

German

Almeidait

English

Almeidaite

Russian

Алмейдаит

CNMNC (IMA)-Number

IMA 2013-020

CNMNC symbol

Symbol

Amd

Locations with GPS information

IDs

GUSID (Global unique identifier short form) k1y2-RSFJ0ac08zPIuwJGg
GUID (Global unique identifier) F9B65C93-8514-4627-9CD3-CCCF22EC091A
Database ID 7583