(Koroit Opal Field, Paroo Shire, Queensland Australia)

This mine is located 80km from the nearest town and has no running water or electricity. All specimens are mined, cut and sold by the mine owner and a small group of miners. This specific opal field was discovered in 1897, with most recent mining operations beginning in 1972 when the popularity of Opals increased. Mining is done by open cut large scale mining or by underground shafts. These opals form as concretions and fracture fillings in a dark silicious ironstone matrix and as wood replacements. Opals from this locality have a unique appearance within their swirled, kernaled, ironstone matrix. Opal is made of hydrous silicon dioxide. The “Play of Color” optical property is the result of a regular arrangement of silica spheres that form a horizontal lattice structure. The gaps in the spheres create a 3 dimensional diffraction grating, with variations in the size of gaps resulting in different “play” of colors. Boulder Opals were formed under specific conditions from aqueous silica gels derived from intense weathering of feldspathic sedimentary rocks under the action of percolating groundwater. The specific factors that were necessary for these opals to form include; a presence of a clean silica gel solution in an undisturbed cavity. There the silica gel could accumulate with time for water to evaporate, which allowed the silica spheres to line up geometrically in the bottom of the cavity. Boulder Opals formed under many cycles of silica percolation and water evaporation, over millions of years. Miners use bulldozers with auger drill bits to drill test holes 30in wide and up to 20m deep to look for traces of opal. Then a bulldozer is used to remove strata and debris, opening up a pit mine. The bulldozer removes sediment carefully as miners look for nodules and seams of color. They must go slowly, as the bright colors of Boulder Opals cannot usually be seen right away. Color saturation and intensity are the main criteria for evaluating the quality of Boulder Opals. Because most Boulder Opals contain the matrix, they are usually sold by piece, not by weight.. Colors and patterns are also important factors. Gem quality Boulder Opals should have 3 or more colors present, according to gemologists, with certain colors being more sought after than others. Red is the rarest color and therefore the most expensive. There are many different patterns that may be found in Boulder Opals, with Harlequin (a display of medium to large angular blocks of color) being the most sought after, and pinfire (a pattern of tiny points of color) being the least. With the unique Matrix Boulder Opal, the composition of the stone in the matrix is taken into account. It must be pleasing to the eye, like a work of art. It is believed that Boulder Opals have less water content than other precious opals, and therefore are much more durable, with little to no cracking or shrinkage. These Opals are known for their deep, intense colors, including deep purple, royal blue and neon green fracture fillings on a brown to black background. Specimens that come from wood replacement have a translucent whitish blue layer, are thicker and do not show as much matrix. Matrix Boulder Opals are the largest precious Opals for their price, and their popularity with artists and craftsmen continues to rise.

– Associated with all chakras, zodiac signs of Scorpio and Virgo & vibrates to the numbers 7, 8 & 9.

– Promotes expansion and actualization
– Allows ones inner light to radiate outwards for others to see.
– Facilitates the ability to see auras.
– Enhances ones beauty, inside and out.
– Brings harmony to relationships.
– Allows one to stay positive an optimistic through disappointments and difficulties until a new path emerges.
– Enhances emotional healing and balancing the auric energy fields.
– Physically eases pain in the lower back and abdomen.

Chemical Formula: SiO₂˖nH₂O
Shape: amorphous
Habit: vein fillings and pseudomorphs of organic materials
Color: brown matrix with light to dark body, red, green, blue purple, yellow, orange, pink etc play of color.
Streak: white
Luster: dull, pearly, waxy or vitreous when raw, vitreous when polished
Diaphaneity: translucent, semi-transparent, opaque
Hardness: 5-6 Mohs
Cleavage: none
Fracture: conchoidal
Specific Gravity: 2.09 g/cm³
Refractive Index: 1.34-1.47