ClassicGems.net

Xonotlite

Discovered in 1866; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

Ca₆Si₆O₁₇(OH)₂

Calcium Silicate Hydroxide

Molecular Weight:

714.99 gm

Composition: 

Classification

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/F.21-30

Nickel-Strunz 10th Ed. ID:

9.DG.35

9 : SILICATES (Germanates)
D : Inosilicates
G : Inosilicates with 3-periodic single and multiple chains

Related to:

None

Varieties:

Mg-bearing Xonotlite

Synonyms:

Calcium-Pectolite, Eakleite, Xenotlite, Xonaltite, Xonolite

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

As needlelike crystals, elongated, to 2 cm, with striated prism zones and tapering terminations; as flaky fibrous radiating bundles and rosettes; massive.

Twinning:

None

Physical Properties

Cleavage:

[001] Perfect

Fracture:

Splintery

Tenacity:

Tough

Moh's Hardness:

6.0 - 6.5

Density:

2.70 - 2.72 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Colorless, White to Chalky White, Gray, light Gray, pale Pink, fading on exposure

Transparency:

Translucent

Luster:

Vitreous, Pearly, Silky

Refractive Index:

1.583 - 1.595  Biaxial ( + )

Birefringence:

0.012

Dispersion:

Very Low

Pleochroism:

None

Occurances

Geological Setting:

In contact metamorphic deposits within limestones, serpentinites, and metavolcanic rocks.

Common Associations:

Apophyllite, Clinohedrite, Diopside, Laumontite, Stilbite, Thaumasite, Tobermorite, Wollastonite

Common Impurities:

Fe, Mn, H₂O

Type Locality:

Tetela de Xonotla, Puebla, Mexico

Year Discovered:

1866

View mineral photos:

Xonotlite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Xonotlite is an extemely rare gem since gem quality crystals are very rare. It is usually found as very small, very thin needlelike crystals or as flaky fibrous radiating bundles and rosettes. Crystals are translucent at best.

There are quite a few localities for finding non-gem quality material that is very attractive and collectable as mineral specimens but gemmy crystals are extremely rare.

Xonotlite gems for sale:

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