Natromontebrasite Mineral Data

General Natromontebrasite Information

Chemical Formula:

(Na,Li)Al(PO4)(OH,F)

Composition:

Molecular Weight = 158.44 gm

Sodium 10.88 % Na 14.67 % Na₂O

Lithium 1.10 % Li 2.36 % Li₂O

Aluminum 17.03 % Al 32.18 % Al₂O₃

Phosphorus 19.55 % P 44.80 % P₂O₅

Hydrogen 0.48 % H 4.26 % H₂O

Oxygen 47.97 % O

Fluorine 3.00 % F 3.00 % F

- % F -1.26 % -O=F₂

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Na_0.75Li_0.25Al(PO₄)(OH)_0.75F_0.25

Environment:

Natromontebrasite (1913) has been shown to be a mixture of an OH-rich amblygonite and lacroixite, with subordinate quantities of wardite.

IMA Status:

Discredited IMA 2006

Locality:

Canyon City and Eight Mile Park, Fremont County, Colorado, USA. Link to MinDat.org Location Data.

Name Origin:

Named for the composition and resemblance to montebrasite.

Name Pronunciation:

Natromontebrasite + Pronunciation

Synonym:

Fremontite

Natromontebrasite Image

Images:

Natromontebrasite

Comments: Pale tan to orange natromontebrasite cleavages in quartz.
Location: Mica Load, Canon City, Fremont County, Colorado, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Natromontebrasite Crystallography

Axial Ratios:

a:b:c =0.7285:1:0.7074

Cell Dimensions:

a = 5.18, b = 7.11, c = 5.03, Z = 2; alpha = 111.035°, beta = 97.818°, gamma = 68.118° V = 158.96 Den(Calc)= 3.31

Crystal System:

Triclinic - Pinacoidal H-M Symbol ( 1) Space Group: P1

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Forms: ( 3 3 2) ( 0 1 1) ( 1 2 0) ( 0 1 0) ( 0 2 1) ( 1 1 0) ( 1 0 0) ( 0 0 1)

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Physical Properties of Natromontebrasite

Cleavage:

{???} Distinct, {???} Distinct, {???} Distinct

Color:

White, Grayish white.

Density:

3.04

Diaphaneity:

Translucent to opaque

Fracture:

Brittle - Uneven - Very brittle fracture producing uneven fragments.

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Hardness:

5.5 - Knife Blade

Luminescence:

Non-fluorescent.

Luster:

Vitreous - Greasy

Streak:

white

Optical Properties of Natromontebrasite

Gladstone-Dale:

CI meas= 0.005 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.077 (Fair) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1841,KPDmeas= 0.1987,KC= 0.1996
Ncalc = 1.61 - 1.65

Optical Data:

Biaxial (+), a=1.594, b=1.603, g=1.615, bire=0.0210

Calculated Properties of Natromontebrasite

Electron Density:

Bulk Density (Electron Density)=2.99 gm/cc
note: Specific Gravity of Natromontebrasite =3.04 gm/cc.

Fermion Index:

Fermion Index = 0.0010523884
Boson Index = 0.9989476116

Photoelectric:

PE_{Natromontebrasite}= 1.64 barns/electron
U=PE_{Natromontebrasite} x rElectron Density= 4.90 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Natromontebrasite is Not Radioactive

Natromontebrasite Classification

Dana Class:

41.05.08.03 (41)Anhydrous Phosphates, etc. Containing Hydroxyl or Halogen

(41.05)where (A B)2 (XO4) Zq

(41.05.08)Amblygonite Group

41.05.08.01 Amblygonite (Li,Na)Al(PO4)(F,OH) P1 1

41.05.08.02 Montebrasite? LiAl(PO4)(OH,F) P1 1

41.05.08.03 Natromontebrasite? (Na,Li)Al(PO4)(OH,F) P1 1

Strunz Class:

08.BB.05 08 - PHOSPHATES, ARSENATES, VANADATES

08.B - Phosphates, etc. with Additional Anions, without H2O

08.BB -With only medium-sized cations, (OH, etc.):RO4 � 1:1

08.BB.05 Amblygonite (Li,Na)Al(PO4)(F,OH) P1 1

08.BB.05 Natromontebrasite? (Na,Li)Al(PO4)(OH,F) P1 1

08.BB.05 Montebrasite? LiAl(PO4)(OH,F) P1 1

08.BB.05 Tavorite LiFe(PO4)(OH) P1 or P1 Tri

Other Natromontebrasite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Natromontebrasite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info

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Natromontebrasite

(Na,Li)Al(PO4)(OH,F)
Dana No: 41.05.08.03 Strunz No: 08.BB.05
Locality:

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