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Searlesite
Current inventory:  0 gems
 

  
Searlesite is named after John W. Searles, California pioneer, who put down the deep well from which type material was extracted. The type locality, Searles Lake is also named after him.

Discovered in 1914;   IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

NaBSi₂O₅(OH)₂

Sodium Boron Silicate Hydroxide

Molecular Weight:

203.98 gm

Composition:

Sodium

11.27 %

Na

15.19 %

Na₂O

Silicon

27.54 %

Si

58.91 %

SiO₂

Boron

5.30 %

B

17.06 %

B₂O₃

Hydrogen

0.99 %

H

8.83 %

H₂O

Oxygen

54.90 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/G.05-10

Nickel-Strunz 10th Ed. ID:

9.EF.15

9 : SILICATES (Germanates)
E : Phyllosilicates
F : Single nets with 6-membered rings, connected by M[4], M[8], etc.

Crystal Data

Crystallography:

Monoclinic - Sphenoidal

Crystal Habit:

Flat crystals, to 17 cm, occur along bedding planes. Commonly as spherulitic aggregates of radiating acicular to prismatic crystals; as massive granular aggregates.

Twinning:

None

Physical Properties

Cleavage:

Perfect on {100}; imperfect on {102}, {010}

Fracture:

Fibrous

Tenacity:

Brittle, Fibrous

Moh's Hardness:

1.0 - 2.0

Density:

2.44 - 2.46 (g/cm³)

Luminescence:

Fluorescent; SW UV = blue green or green, LW UV = orange

Radioactivity:

Not Radioactive

Other:

Piezoelectric

Optical Properties

Color:

Colorless, White, light Brown

Transparency:

Translucent to Transparent

Luster:

Vitreous, slightly pearly on cleavage surfaces

Refractive Index:

1.515 - 1.535  Biaxial ( - )

Birefringence:

0.0110 - 0.0200

Dispersion:

None

Pleochroism:

None

Occurances

Geological Setting:

Commonly interbedded with oil shales or marls (Green River Formation, USA); in boron-bearing evaporite deposits (California, USA); rarely in vugs in phonolite (Point of Rocks, New Mexico, USA).

Common Associations:

Shortite, Trona, Pyrite (Green River Formation, USA); "Opal" (Cave Springs Wash, Nevada, USA)

Common Impurities:

Al,Fe,Mg,H₂O

Type Locality:

Searles Lake, San Bernardino County, California, USA

Year Discovered:

1914

View mineral photos:

Searlesite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Searlesite is a rare silicate mineral that is rarely available faceted due to its soft and fibrous nature. It is not an attractive gem but one that is for collectors of the very unusual. Searlesite is a Piezoelectric mineral, meaning that it has the ability to generate a voltage in response to applied mechanical stress. Relatively large crystals are usually flat and fibrous and occur along bedding planes. Tiny transparent prismatic crystals are much too small for faceting.

Searlesite can be found in the USA, at Searles Lake, San Bernardino County, in the Kramer borate deposit, Kern County, and at Lake Tecopa, Inyo County, California; widespread in the Green River Formation of Utah and Wyoming; from Cave Springs Wash, Silver Peak Range, Esmeralda County, Nevada; and at Point of Rocks, Colfax County, New Mexico. In Canada, at Mont Saint-Hilaire, Quebec. From Kremna, near Tito Uzice; Lopare; and near Bela Stena, Yugoslavia.
 

  
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