Sapphirine-1A

Formula:

(Mg,Al,Fe

)

[(Al,Si,Fe

)

System:

Triclinic

A polytype of Sapphirine

1-layer triclinic polytype, less common in nature than the 2M polytype.

Classification of Sapphirine-1A

IMA status:

Not Approved

Explanation of status:

Polytype, not a distinct species

Hey's CIM Ref.:

16.7.3

16 : Silicates Containing Aluminum and other Metals
7 : Aluminosilicates of Mg

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Physical Properties of Sapphirine-1A

Lustre:

Vitreous

Comment:

similar range to Sapphirine-2M

Tenacity:

Brittle

Crystallography of Sapphirine-1A

Crystal System:

Triclinic

Class (H-M):

1 - Pinacoidal

Space Group:

Cell Parameters:

a = 10.04Å, b = 10.38Å, c = 8.65Å
α = 107.6°, β = 95.1°, γ = 123.9°

Ratio:

a:b:c = 0.967 : 1 : 0.833

Unit Cell Volume:

V 674.36 Å³ (Calculated from Unit Cell)

Twinning:

repeated lamellar twinning on (0-11), which is equivalent to (010) of the monoclinic polytypes.

Comment:

Merlino (1980)

Chemical Properties of Sapphirine-1A

Formula:

(Mg,Al,Fe

)

[(Al,Si,Fe

)

Essential elements:

Al, Mg, O

All elements listed in formula:

Al, Fe, Mg, O, Si

Analytical Data:

Stabilised relative to the 2M structure by lower Fe2+, higher Fe3+, lower Be, lower temperature and/or higher pressure. Christy (1989), Christy et al. (2002).

Relationship of Sapphirine-1A to other Species

16.7.1

Pyrope

[SiO

]

16.7.2

Sapphirine

(Mg,Fe)

4-x

4+x

[Al

4+x

2-x

16.7.4

Magnesiochloritoid

MgAl

[O|(OH)

|SiO

]

16.7.5

Kulkeite

Al(AlSi

(OH)

16.7.6

Palygorskite

(Mg,Al)

(Si,Al)

(OH)

·8H

16.7.7

Saponite

0.25

(Mg,Fe)

(Si,Al)

(OH)

·nH

16.7.8

Aliettite

0.2

(Si,Al)

(OH)

·4H

16.7.9

Montmorillonite

(Na,Ca)

0.33

(Al,Mg)

(OH)

·nH

16.7.10

Baumite

(Mg,Al,Mn,Zn,Fe)

(Si,Al)

(OH)

Other Names for Sapphirine-1A

Synonyms:

Sapphirine-1Tc

Other Languages:

Russian:	Сапфирин-1Tc

Other Information

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 Sapphirine-1A

Reference List:

McKie, D. (1963) Order-disorder in sapphirine. Mineralogical Magazine: 635-645.

Merlino, S. (1973) Polymorphism in sapphirine. Contribs Mineral Petrol: 41: 21-29. Abstract in American Mineralogist (1974): 59: 632.

Merlino, S. (1980) The crystal structure of sapphirine-1Tc. Zeitschrift für Kristallographie: 151: 91-100.

Christy, A.G. and Putnis, A. (1988) Planar and line defects in the sapphirine polytypes. Phys Chem Minerals: 15: 548-558. Abstract in American Mineralogist (1990): 75: 937.

Christy, A.G. (1989) The effect of composition, pressure and temperature on the stability of the 1Tc and 2M polytypes of sapphirine. Contribs Mineral Petrol 103: 203-215.

Christy, A.G., Tabira, Y., Hölscher, A., Grew, E.S., Schreyer, W. (2002) Synthesis of beryllian sapphirine in the system MgO-BeO-Al2O3-SiO2-H2O and comparison with naturally occurring beryllian sapphirine and khmaralite, Part 1: experiments, TEM and XRD. American Mineralogist: 87: 1104-1112.