CATAPLEIITE

Catapleiite – Na2Zr(Si3O9)·2H2O – is a very rare cyclosilicate, occurring in alkaline plutonic rocks. It is not important as an ore, but crystals fetch very high prices in the collector’s mineral market, on the order of several thousand dollars per piece.

It is classified in the Catapleiite Group, being the monoclinic dimorph of gaidonnayite. It forms a series with calciocatapleiite and may contain Ca and Fe. It exhibits green fluorescence under shortwave and longwave ultraviolet light.

1. Characteristics

Crystal system: Monoclinic prismatic, pseudohexagonal.          

Color: Dark brown, reddish brown, flesh red, yellowish red, colorless, light gray, beige, light yellow, orange, light blue.

Habit:  Thin, tabular, pseudohexagonal crystals, up to 15 cm. Forms pseudohexagonal rosettes of tabular crystals.      

Cleavage:  {100} perfect, {101} and {102} bad. 

Tenacity: Brittle.        

Twinning: Polysynthetic in 30, 60 and 90 degrees.

Fracture: Irregular, conchoidal.       

Mohs Hardness: 5.5 – 6

Parting: No.         

Streak: White to pale yellow.         

Lustre: Vitreous to dull.          

Diaphaneity: Transparent.           

Density (g/cm³):  2.65 – 2.9

 

2. Geology and Deposits

Catapleiite typically occurs as an accessory mineral in plutonic igneous rocks such as sodalite-syenites and nepheline syenites.

It also occurs in pegmatites and veins associated with these rocks, typically as a product of the metasomatic alteration of eudyalite.

It can occur as a primary mineral, both in phenocrysts and in the rock matrix, in eudyalite-syenites (grennaites) (Norra Karr Alkaline Complex, Sweden).

 

3. Mineral Associations

In the type locality (Langesundsfjorden, Norway) it is associated with zircon, aegirine, leucophanite, mosandrite-(Ce) and tritomite-(Ce).

It is associated with some well known minerals such as microcline, fluorite, natrolite, sodalite and analcime.

It occurs with rare minerals such as mangano-neptunite, epidymite, genthelvite, polylithionite, rinkite, lavenite, astrophyllite, and petarasite.

 

4. Transmitted Light Microscopy

Refraction indices:  nα: 1.591    nβ:  1.592     nγ: 1.627

PLANE POLARIZED LIGHT – PPL

Color / Pleochroism: Colorless. 

Relief: Moderate. 

Cleavage: {100} perfect, {101} and {102} bad.

Habits: Tabular, pseudohexagonal.      

CROSSED POLARIZED LIGHT – XPL

Birefringence and Interference Colors: Maximum birefringence of 0.036, corresponding to first and second order colors, up to the end of the second order, very colorful: reds, blues, greens, violets, etc. 

Extinction: No information available.           

Elongation sign: No information available.

Twins: No information available.            

Zoning: No information available.                

CONVERGENT LIGHT

Character: B(+), may be U(+).          

2V angle: 40º         

Alterations: No information available.           

May be confused with:  No information available.         

Caption

5. Reflected Light Microscopy

Reflected light microscopy is not the recommended analytical method for the identification of catapleiite. However, it is important to make a polished thin section or a polished section to identify the opaque minerals that occur associated with catapleiite.

Sample preparation:        

PLANE POLARIZED LIGHT – PPL

Reflection color:        

Pleochroism:       

Reflectivity:         

Bireflectance:        

CROSSED POLARIZED LIGHT – XPL

Isotropy / Anisotropy:         

Internal reflections:       

May be confused with:        

General Characteristics: 

Caption