Tinzenite
Current inventory:  0 gems
 

  
Tinzenite is named after its discovery locality, Alpe Parsettens, near Tinzen, Grisons, Switzerland.

Discovered in 1923;   IMA status:  Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

(Ca,Mn^2+,Fe²⁺)₃Al₂BSi₄O₁₅(OH)

Calcium Manganese Iron Aluminum Boron Silicate Hydroxide

Molecular Weight:

572.45 gm

Composition:

Calcium

12.60 %

Ca

17.63 %

CaO

Manganese

8.64 %

Mn

11.15 %

MnO

Aluminum

9.43 %

Al

17.81 %

Al₂O₃

Iron

2.93 %

Fe

3.77 %

FeO

Silicon

19.63 %

Si

41.98 %

SiO₂

Boron

1.89 %

B

6.08 %

B₂O₃

Hydrogen

0.18 %

H

1.57 %

H₂O

Oxygen

44.72 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/E.06-40

Nickel-Strunz 10th Ed. ID:

9.BD.20

9 : SILICATES (Germanates)
B : Sorosilicates
D : Si₂O₇ groups, with additional anions; cations in tetrahedral [4] and greater coordination

Related to:

Axinite Group. Axinite-(Mn)-Tinzenite Series.

Members of Group:

Axinite Group: Axinite-(Fe), Axinite-(Mg), Axinite-(Mn), Tinzenite

Varieties:

None

Synonyms:

None

Crystal Data

Crystallography:

Triclinic - Pinacoidal

Crystal Habit:

As aggregates of prismatic crystals, to 5 mm; massive.

Twinning:

None

Physical Properties

Cleavage:

Good on {100}; Poor on {001}, {110}, {011} (by analogy to the Axinite Group).

Fracture:

Irregular/Uneven to Conchoidal

Tenacity:

Brittle

Moh's Hardness:

6.5 - 7.0

Density:

3.355 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Yellow, Brownish Yellow-Green, Orange, Red; Orange to Red in thin section

Transparency:

Transparent to Subtranslucent

Luster:

Vitreous

Refractive Index:

1.690 - 1.705  Biaxial ( - ) 

Birefringence:

0.0110

Dispersion:

Weak to Distinct

Pleochroism:

In thick sections, weak; X = light brown; Y = violet; Z = light yellow or colorless

Occurances

Geological Setting:

In metamorphosed manganese-bearing ophiolites (Liguria, Italy); in quartz veins in cherts of the greenschist facies (Akatore, New Zealand).

Common Associations:

Braunite, Quartz

Common Impurities:

Ti, Mg, Ba, Na, K, H₂O

Type Locality:

Parsettens Alp, Tinizong (Tinzen), Oberhalbstein (Surses; Sursass), Albula Valley, Grischun (Grisons; Graubünden), Switzerland

Year Discovered:

1923

View mineral photos:

Tinzenite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Tinzenite is a rare boron silicate mineral that is rarely available as a faceted gem. Tinzenite is a member of the Axinite Group of minerals that also includes Axinite-(Fe), Axinite-(Mg) and Axinite-(Mn). Tinzenite's bright orange color makes for very attractive mineral specimens or faceted gems. Gems are suitable for jewelry with a Mohs hardness of 6.5 - 7.0.

Distribution: From near Tinzen, in the Val d'Err, Graubünden, Switzerland. In the Cassagna and Gambatesa mines, Val Graveglia, near Chiavari, Liguria, Italy. From Akatore, New Zealand.
 

  
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