Boulder opal

Boulder Opal Facts, Information and Description
See opal jewelry
The gemstone Opal is the official October birthstone as adopted by the American National Association of Jewelers in 1912. It is also the birth stone for the Zodiac sign of Libra.

Boulder Opal
Boulder opal is a naturally formed solid opal which consists of a fine layer of opal that has been deposited by nature on and in the fissures of ironstone base rock.

Boulder Opal from Queretaro Mexico
Polished Mexican Opal
Fire opal mining in Mexico dates back several hundred years, and the main mining region is located near the town of Magdalena in Jalisco, Mexico, and later in the state of Querétaro.

Gemology -- Apatite to Boulder Opal
Andalusite:
Andalusite is named after Andalusia, which is one of 17 autonomous communities that constitute Spain.

Boulder Opal
Boulder opal is found sparsely distributed over a wide area of Australian ironstone or boulder country where the opal (silica mix) fills veins, cracks, cavities and crevices in ironstone boulders.

Boulder Opal, formed in a sandstone matrix called ironstone, has light flashes of blue against a rich pattern of dark brown, reddish brown, and tan.

Boulder Opal
Boulder Opal forms on a dark ironstone base (the host rock) and occurs as a thin uneven layer adhering to the ironstone. Because of the uneven layers, sometimes part of the ironstone is visible on the surface of the stone.

Boulder Opal - It possess natural brown body colour or the back that appears black from the front. It is too available in all colour variations. Often it possesses rolling surface and ironstone inclusions. It can be given any innovative cut.

Boulder Opal Agate
The term "agate opal" refers to both opals with agate-like bands of color and agates with alternating bands of common opal. We believe our boulder opal is the latter.

[Boulder opals-not assembled stones}
Opal triplets have a colorless, usually somewhat domed, cap cemented to the doublet.

Boulder Opal - opal found in ironstone concretions within sandstone formations. This opal often is so thin that the finished gem must include the natural matrix backing. Yowah nuts and pipe opal are types that yield solid opal.

Boulder opal is a precious opal cut to retain some of the surrounding opal matrix, resulting in a unique opal look. It has a dark base surface and can display exciting play of color. On Mohs' scale of hardness, boulder opal is 1.98-2.50.

White opal, rough opal, fire opal, crystal opal, black and boulder opal and more all explode with a variety of color to outstrip the rainbow. Dozens of dazzling hues pulsate with an iridescence known as ‘fire’.

Winter 1973, A new opal doublet to look like boulder opal, p. 233, 1p.
Summer 1974, Treating Matrix Opal, p. 306, 3pp.
Summer 1974, Synthetic opal, p. 309, 3pp.
Fall 1974, Imitation opal on matrix, p. 331, 2pp.

Boulder Opal is a combination of matrix or "mother" rock with Opal attached to it. Boulder Opals are often carved, using the dark brown rock and colorful Opal for contrast.

Deep caves in Australia were first discovered in 1872, producing thin veins of very fine quality boulder opals. This thin but brilliant colored boulder opal was primarily used for carving cameos.

The White opal, Black Opal, Opal Matrix, Boulder Opal, Harlequin Opal, Jelly Opal, and Crystal Opal fall into this category.
The Fire Opal usually does not show any play-of-color.

Another more unusual type of opal is boulder opal, which has opal with an ironstone host rock matrix which creates a natural dark background to view its fire.

It is subdivided in three groups: black opal, white opal, milk opal and Boulder opal; fire opal; and common opal. The first group contains the most expensive gemstones and displays a luster of rainbow colors which constantly changes.

Boulder Opal - opal with play-of-color that is present in a matrix of dark brown or black sandstone (ironstone).

Boulder Opals are recognized by their dark blue and green color with spots of red. White Opal, being most popular in birthstone jewelry, displays orange-red and greenish-yellow fire. Mexican Fire Opals are recognized for its pumpkin orange color.

Fire and water, the sparkling images of Boulder Opal, the vivid light flashes of Black Opal or the soft shine of Milk Opal - striking contrasts characterise the colourful world of this fascinating gemstone.

Boulder opal combines precious opal with the ironstone in which it forms. Bright yellow, orange, or red fire opal are quite different from the other varieties of opal.

Boulder Opal foster creativity and originality. Fire Opal inspires dynamic energy and intensity. Sonoma Opal induces emotional stability. White Opal enhances competency and efficiency.
Birthstone: October (Hope, faith, confidence).

Matrix: The natural rock or mineral in which a gemstone is embedded. Boulder opals have a natural matrix base, and turquoise sometimes has black matrix throughout ("spiderweb" turquoise).

These gemstones are differentiated on the basis of the variety, place of occurrence, and color of the main body, into Dark or Black Opal, White or Light Opal, Milk or Crystal Opal, Boulder Opal, Opal Matrix, Mexican and Fire Opal.

group of fine Opals include quite a number of wonderful gemstones which are differentiated on the basis of the variety, place of occurrence, and color of the main body, into Dark or Black Opal, White or Light Opal, Milk or Crystal Opal, Boulder Opal, ...

See also: Stone, Opal, Gemstone, Jewel, Color