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Benitoite

 

Benitoite

 

Discovered in 1907; IMA status: Valid (pre-IMA; Grandfathered)

 

Chemistry

 

 

Chemical Formula:

BaTiSi3O9

 

Barium Titanium Silicate

Molecular Weight:

413.46 gm

Composition:

Barium

33.21 %

Ba

37.08 %

BaO

 

Titanium

11.58 %

Ti

19.32 %

TiO2

 

Silicon

20.38 %

Si

43.60 %

SiO2

 

Oxygen

34.83 %

O

 

 

 

 

100.00 %

 

100.00 %

= TOTAL OXIDE

Classification

   

   

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/E.01-10

Nickel-Strunz 10th Ed. ID:

9.CA.05

 

9 : SILICATES (Germanates)
C : Cyclosilicates
A : [Si3O9]6- 3-membered single rings (dreier-Einfachringe), without insular complex anions

Related to:

Benitoite Group. The titanium analogue of Pabstite. Related to Rogermitchellite.

Members of Group:

Benitoite Group: Benitoite, Bazirite, Pabstite, Wadeite

Varieties:

None

Synonyms:

Benitoide

 

 

Crystal Data

   

   

Crystallography:

Hexagonal - Ditrigonal Dipyramidal

Crystal Habit:

Flat pyramidal crystals, tabular, triangular or hexagonal in outline, to 6 cm.

Twinning:

By rotation about [0001]

 

 

Physical Properties

   

 

Cleavage:

Poor on [1011]

Fracture:

Conchoidal

Tenacity:

Brittle

Moh's Hardness:

6.0 - 6.5

Density:

3.64 - 3.68 (g/cm3)

Luminescence:

Fluorescent; blue under SW UV; intense blue Cathodoluminescence

Radioactivity:

Not Radioactive

 

 

Optical Properties

   

   

Color:

Sapphire-blue, purplish-blue, white to colorless, pink; commonly bicolored.

Transparency:

Transparent to translucent

Luster:

Vitreous

Refractive Index:

1.756 - 1.804  Uniaxial ( + )

Birefringence:

0.047

Dispersion:

0.046 (greater than diamond)

Pleochroism:

Visible; O = colorless; E = purple, indigo, greenish blue

 

 

Occurances

   

   

Geological Setting:

In natrolite veins cutting glaucophane schist in a serpentine body (San Benito Co., California, USA); in a magnesio-riebeckite-quartz-phlogopite-albite dike cutting serpentinite (Ohmi, Japan).

Common Associations:

Joaquinite, Natrolite, Neptunite (San Benito Co., California, USA); Ohmilite, Bario-Orthojoaquinite, Leucosphenite (Ohmi, Japan).

Common Impurities:

Na

Type Locality:

Dallas Gem Mine (Gem Mine; Benitoite Mine), New Idria District, San Benito County, California, USA

Year Discovered:

1907

View mineral photos:

Benitoite Mineral Photos and Locations

 

 

Unusual Gem Categories

   

   

 

Fluorescent Gems

 

 

More Information

   

   

 

Mindat.org
Webmineral.com

 

 

Benitoite is a rare barium titanium silicate mineral that is one of the rarest and most beautiful of all gems. Benitoite has the color of fine blue Sapphire and dispersion slightly higher than that of Diamond! Added to those impressive features are the purple it displays due to its pleochroism and the bright bluish-white glow it exhibits under shortwave UV light and you have one of the most spectacular of all gems. If that wasn't impressive enough, to add to its rarity, Benitoite is a one source gem coming from only one location in the world. Benitoite has been found at a few localities worldwide, but gem quality crystals only come from the Benitoite Gem Mine (also known as the Dallas Gem Mine) in San Benito County, California, USA. The Benitoite Gem Mine is now closed and only surface collecting is allowed. Benitoite was named California's state gemstone in 1985.

Benitoite gems are most known for their blue to purplish blue colors but are also occassionally available as colorless and rarely, pink. A few colorless gems have been treated by a secret process that turns them light orange. Benitoite gems have a very impressive dispersion (fire and brilliance) of 0.046 that is slightly greater than that of Diamond at 0.044. Benitoite exhibits a beautiful blue to bluish white fluorescence under shortwave UV light and an intense blue cathodoluminescence. If you hover your cursor over the Benitoite picture at the top of this page you will see the beautiful blue glow of the Benitoite gem under shortwave UV light. With a Mohs hardness of 6.0 - 6.5 and poor cleavage, Benitoite gems are suitable for jewelry.

Benitoite is a very rare and dersirable gem but is also very desirable and collectible as a mineral specimen. Benitoite specimens frequently feature a very aesthetic collection of blue, pyramidal, triangular Benitoite crystals associated with lustrous black Neptunite crystals and orange Joaquinite crystals on a bed of bright white Natrolite crystals on a grayish blue Glaucophane Schist matrix.

Benitoite was first identified, described and named in 1907 by American geologist George Davis Louderback (1874–1957). He named it Benitoite for its occurrence in San Benito County, California. Louderback also described and named another new mineral often associated with Benitoite, Joaquinite, which he named after Joaquin Ridge, located near the Benitoite Gem Mine.

Benitoite distribution: in the USA, in California, at the Benitoite Gem Mine, Mina Numero Uno, the Victor and Junilla claims, and on Santa Rita Peak, San Benito County; from the Big Creek-Rush Creek District, Fresno County; and on Trumbull Peak, Mariposa County; in the Diamond Jo quarry, Magnet Cove, Hot Spring County, Arkansas. From Kinzandani, Hashidate, Ohmi, Itoigawa City, Niigata Prefecture, Chubu Region, Honshu Island, Japan. At Šebkovice, Třebíč, Vysočina Region, Moravia, Czech Republic.

Benitoite gems for sale:

Benitoite-003

Gem:

Benitoite

Stock #:

BENI-003

Weight:

3.0910 ct

Size:

10.42 x 7.50 x 5.40 mm

Shape:

Fancy - Shield

Color:

Purplish-Blue

Clarity:

85% Loupe Clean - 15% SI2

Origin:

San Benito Gem Mine, CA, USA

Treatment:

None (natural)

Price:

$9,000.00

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

Benitoite-003

This extemely rare gem is from the now closed Benitoite Gem Mine in San Benito County, California, USA - the only location in the world for gem-quality Benitoite. OK, so if a two carat Benitoite is extremely rare; then a three carat Benitoite is exceedingly rare! The color of this gem is ideal for Benitoite (a beautiful purplish-blue). This gem is about 85% loupe clean with two feather inclusions and one very small nick at the girdle. Just the fact that this Benitoite is ideal color and over three carats makes this gem a true rarity! It was precision faceted in the US. This Benitoite includes an EGL USA appraisal of $9,800.00! (Report # US 40237301C).


Benitoite-009

Gem:

Benitoite

Stock #:

BENI-009

Weight:

0.970 ct

Size:

6.2 mm diameter

Shape:

Round

Color:

Medium Blue with Purple highlights

Clarity:

SI2

Origin:

San Benito Gem Mine, CA, USA

Treatment:

None (natural)

Price:

$950.00    [ Make an offer ]

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

Benitoite-009

Here is a large round Bentioite! As most Benitoite collectors know, this is considered large for such a clean and well cut gem. It is a .97ct, medium blue gem that is slightly included. It measures 6.2mm in diameter. There are a few small veils in the pavilion as well as a bit of matrix inclusion that is also tucked away in the pavilion. This is actually very clean for such a large Benitoite gem.


Benitoite-004

Gem:

Benitoite

Stock #:

BENI-004

Weight:

0.3850 ct

Size:

4.68 x 2.73 mm

Shape:

Round Brilliant

Color:

Blue

Clarity:

Loupe Clean

Origin:

San Benito Gem Mine, CA, USA

Treatment:

None (natural)

Price:

$420.00    [ Make an offer ]

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

Benitoite-004

This beautiful gem really shows the extreme brilliance and fire of Benitoite. The precision faceting brings out the best in this gem. The color is a medium blue with flashes of purple. As usual, the pictures can't capture the true beauty of the gem. This gem was precision faceted in the US.


Benitoite-005

Gem:

Benitoite

Stock #:

BENI-005

Weight:

2.2175 ct

Size:

10.28 x 8.07 x 4.64 mm

Shape:

Fancy - Pear

Color:

Pale Blue

Clarity:

Eye Clean - VVS

Origin:

San Benito Gem Mine, CA, USA

Treatment:

None (natural)

Price:

$6,400.00    [ Make an offer ]

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

Benitoite-005

A very large and unique Benitoite with pale blue color and a slightly sleepy appearance due to very fine Natrolite fibers. This gem was cut in the US and is very well faceted in an elongated trillion/pear shape. The color is lighter than most Benitoites which allows its brilliance to show very well. It is a very bright and beautiful gem.


Benitoite-006

Gem:

Benitoite

Stock #:

BENI-006

Weight:

0.1375 ct

Size:

3.48 x 2.65 x 1.82 mm

Shape:

Oval

Color:

Colorless

Clarity:

Eye Clean

Origin:

San Benito Gem Mine, CA, USA

Treatment:

None (natural)

Price:

$85.00

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

Benitoite-006

A very rare colorless Benitoite from the closed Benitoite Gem Mine in San Benito County, California, USA.


Benitoite-007

Gem:

Benitoite

Stock #:

BENI-007

Weight:

0.3305 ct

Size:

4.25 x 2.72 mm

Shape:

Round

Color:

Blue

Clarity:

Eye Clean

Origin:

San Benito Gem Mine, CA, USA

Treatment:

None (natural)

Price:

$350.00    [ Make an offer ]

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

Benitoite-007

This beautiful gem really shows the extreme brilliance and fire of Benitoite. The precision faceting brings out the best in this gem. The color is a medium blue with flashes of purple. This gem was precision faceted in the US.


Benitoite-002

Gem:

Benitoite

Stock #:

BENI-002

Weight:

2.0100 ct

Size:

7.17 x 8.55 x 5.26 mm

Shape:

Fancy - Kite

Color:

Purplish-Blue

Clarity:

Flawless! Loupe Clean

Origin:

San Benito Gem Mine, CA, USA

Treatment:

None (natural)

Price:

SOLD (but we have others)

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

Benitoite-002

This extemely rare gem is from the now closed Benitoite Gem Mine in San Benito County, California, USA - the only location in the world for gem-quality Benitoite. A two carat Benitoite is very rare; a flawless two carat Benitoite is extremely rare! The color of this gem is ideal for Benitoite (a beautiful purplish-blue), the faceting is supurb! It was precision faceted in the US. This gem has lots of fire and brilliance - it is nothing short of breath-taking!

Click here for larger pictures of BENI-002.


Benitoite-008

Gem:

Benitoite

Stock #:

BENI-008

Weight:

0.2250 ct

Size:

3.70 diameter x 2.30 mm depth

Shape:

Round

Color:

Deep purple/blue

Clarity:

Flawless (loupe clean)

Origin:

San Benito Gem Mine, CA, USA

Treatment:

None (natural)

Price:

SOLD (but we have others)

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

Benitoite-008

This beautiful, rare gem is from the now closed Benitoite Gem Mine in San Benito County, California, USA - the only location in the world for gem-quality Benitoite. The color is beautiful, the clarity is flawless and the faceting is excellent.


Benitoite-001

Gem:

Benitoite

Stock #:

BENI-001

Weight:

0.3700 ct

Size:

4.71 x 3.25 x 2.68 mm

Shape:

Cut corner rectangle

Color:

Blue w/ purple highlights

Clarity:

Flawless (loupe clean)

Origin:

San Benito Gem Mine, CA, USA

Treatment:

None (natural)

Price:

SOLD (but we have others)

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

Benitoite-001

This beautiful, rare gem is from the now closed Benitoite Gem Mine in San Benito County, California, USA - the only location in the world for gem-quality Benitoite. The color is beautiful, the clarity is flawless and the faceting is excellent.


 


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