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Magnesio-riebeckite
Current inventory:  0 gems
 

Magnesio-riebeckite

  
M
agnesio-riebeckite was named in 1957 by Akiho Miashiro for its composition containing magnesium and its relationship to Riebeckite. Riebeckite is named for famous eighteenth century German explorer and minerologist, Emil Riebeck (1853 - 1885).

Discovered in 1949;  IMA status:  Valid (pre-IMA; Grandfathered)

 

Chemistry

 

 

Chemical Formula:

Na2[(Mg,Fe2+)3Fe3+2]Si8O22(OH)2

 

Sodium Magnesium Iron Silicate Hydroxide

Molecular Weight:

876.08 gm

Composition:

Potassium

0.13 %

K

0.16 %

K2O

 

Sodium

4.09 %

Na

5.52 %

Na2O

 

Calcium

1.97 %

Ca

2.75 %

CaO

 

Magnesium

5.35 %

Mg

8.88 %

MgO

 

Titanium

0.16 %

Ti

0.27 %

TiO2

 

Manganese

0.31 %

Mn

0.45 %

Mn2O3

 

Aluminum

0.80 %

Al

1.51 %

Al2O3

 

Iron

17.47 %

Fe

12.06 %

FeO / 11.57 % Fe2O3

 

Silicon

25.65 %

Si

54.87 %

SiO2

 

Hydrogen

0.23 %

H

2.06 %

H2O

 

Oxygen

43.83 %

O

 

 

 

 

100.00 %

 

100.10 %

= TOTAL OXIDE

 

 

Classification

   

   

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/F.08-40

Nickel-Strunz 10th Ed. ID:

9.DE.25

 

9 : SILICATES (Germanates)
D : Inosilicates
E : Inosilicates with 2-periodic double chains, Si
4O11; Clinoamphiboles

Related to:

Riebeckite Group, Sodium Amphibole Subgroup, w(OH, F, Cl)-dominant Amphibole Group, Amphibole Supergroup. Magnesioriebeckite - Ribeckite Series. Glaucophane - Riebeckite - Kozulite Series. Magnesio-riebeckite is defined as a member of the Riebeckite Group with Mg>Fe2+ in the C2+ position and (OH) in the W position.

Members of Group:

Riebeckite Group: Fluoro-riebeckite, Magnesio-fluoro-riebeckite, Riebeckite

Varieties:

None

Synonyms:

Babadudenite, Ferri-glaucophane, Magnesian-riebeckite, Rhodusite, Svidneite, Ternovskite, Torendikite, Torendrickite, Torendrikite

 

 

Crystal Data

   

   

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

Rarely as prismatic crystals. Also columnar, fibrous, or granular aggregates.

Twinning:

Simple or multiple twinning || {100}.

 

 

Physical Properties

   

 

Cleavage:

Perfect on {110}; intersecting at ~58 and ~122; partings on {010}, {001}.

Fracture:

Conchoidal to Uneven

Tenacity:

Brittle

Moh's Hardness:

5.0 - 6.0

Density:

3.12 - 3.29 (g/cm3)

Luminescence:

None

Radioactivity:

Not Radioactive

Health Warning:

The asbestiform variety of Magnesio-riebeckite can cause lung disease when inhaled, as in other species of asbestos minerals.

 

 

Optical Properties

   

   

Color:

Light Blue, Dark Blue, Blackish Blue, Black

Transparency:

Translucent to Opaque

Luster:

Vitreous, Silky

Refractive Index:

1.668 - 1.680  Biaxial ( - ) or ( + )

Birefringence:

0.0120

Dispersion:

r > v or r < v

Pleochroism:

Strong; X = dark blue; Y = indigo; Z = yellow-green

 

 

Occurances

   

   

Geological Setting:

In granulites, ironstones, ferruginous metacherts, greenschist facies schists, and carbonatites. Veins in slightly metamorphosed sandstone and carbonates associated with evaporites.

Common Associations:

Epidote, Muscovite, Quartz, Stilpnomelane, Winchite

Common Impurities:

Ti, Al, Mn, Ca, K, H2O

Type Locality:

Alto Chapare District, Chapare Province, Cochabamba Department, Bolivia

Year Discovered:

1949

View mineral photos:

Magnesio-riebeckite Mineral Photos and Locations

 

 

More Information

   

   

 

Mindat.org
Webmineral.com

 

 


M
agnesio-riebeckite is a rare gem that is not well known in the gem market. It is also known by the synonym Rhodusite which is named for the Greek island of Rhodes (Rhodus in historic times) where it was found by Bukowski in 1889. Magnesio-riebeckite is usually found as fibrous "asbestiform" masses but a very few sources produce solid, opaque, massive material of light to dark blue that can be used to create attractive cabochons.

Magnesio-riebeckite may have originally been discovered by C. Palache in 1928 at the mines at Franklin, New Jersey, USA, but the specimen was incorrectly identified as Crocidolite. The year of discovery is noted as 1949 from the type locality of Alto Chapare District, Chapare Province, Bolivia. Magnesio-riebeckite and Riebeckite are closely related to the mineral Glaucophane. Glaucophane is named for its typical blue color. The name Glaucophane is from the Greek glaukos for "sky-blue" and phainestrai for "to appear", in allusion to its typical color. The blue color is very diagnostic for the two species and both are the only common amphibole minerals that are typically blue.

There are many localities for finding the fibrous "asbestiform" material but only one source for the attractive solid, deep blue massive material: Krivoy Rog Basin, Dnipropetrovs'k Oblast' (Dnepropetrovsk Oblast'), Ukraine.
 

  
M
agnesio-riebeckite gems for sale:

Magnesioriebeckite-001

Gem:

Magnesio-riebeckite

Stock #:

MAGNESIOR-001

Weight:

20.9165 ct

Size:

44.02 x 11.92 x 4.68 mm

Shape:

Elongated Shield cabochon

Color:

Blue

Clarity:

Opaque

Origin:

Krivoy Rog Basin, Dnipropetrovs'k Oblast', Ukraine

Treatment:

None (natural)

Price:

SOLD

Pictures are of the actual gem offered for sale.
Gem images are magnified to show detail.

Magnesioriebeckite-001

A very rare gem with a beautiful blue color. This cabochon gem is formed in an elongated shield shape. It is from the Kokchetav Massif in northern Kazakhstan.


 


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