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The Gemstone Montana Sapphire

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Montana Sapphire Gemstones
PHYSICAL PROPERTIES
Chemistry: Al2O3
Composition: Aluminum Oxide
Class: Oxides and Hydroxides
Group: Hematite
Crystal System: trigonal; bar 3 2/m
Fracture: conchoidal
Hardness: 9
Specific Gravity: 3.99 - 4.0
Refractive Index: 1.757 - 1.779
Luster: vitreous to adamantine
Streak: white
Color: Most any color some stones show zoning
Cleavage: is absent, although there is parting which occurs in three directions
Transparency: Crystals are transparent to translucent
Associated Minerals: calcite, feldspars, garnets, micas and zoisite

DISTINGUISHING CHARACTERISTICS:
Advances in sapphire heat treatment over the past two decades has opened the doors to competition. It is an established fact that 90 percent of all gem grade sapphire is heat-treated. Montana sapphire boasts a rainbow of colors when properly treated. It is also renowned for its high refractive index when properly cut and its ability to retain brilliance under a variety of lighting conditions.

This process improves the sapphires, both in color and clarity. The heating process does not use artificial coloring of any type, it simply causes a property change in the stone that dissolves an element called rutile, eliminating the cloudiness often seen in sapphires. The difference between natural and heated stones is dramatic. Some stones are left in their natural state, particularly if they are gem quality. Only about 3-5% of Montana Sapphires are gem quality as found.

An additional consideration when deciding whether to heat or not is the color of the stone. Occasionally a stone is such a spectacular color, that one has to decide whether or not to risk the possible color change that may occur as a result of heating. There is no way to know for sure what the end result will be, and sometimes the decision is made to leave the stone in its natural state in order to retain the color.

 
ENVIRONMENT:
Of the four Montana sapphire regions, only Rock Creek (just outside Philipsburg) Is known for its variety of distinctly crisp and sharp colors. As tastes have shifted to more brilliant gem jewelry, Rock Creek sapphires have come into their own. Particularly with the advent of readily available heat treating.

Rock Creek sapphires are able to fill a niche worldwide. Colors range from the classic "cornflower blue" to "red-orange" and "mint green." The colorful variety of sapphires found and finished here have a character and beauty all their own.


LOCALITIES:
Montana is home to some of the largest Sapphire deposits in the world. Known as the "Native American Sapphire" Montana Sapphires are available in every imaginable color of the rainbow. Montana Sapphires are considered "Fancy" Sapphires, ( colors other than, but also including Blue ). Many experts rate Montana Sapphires as "The Finest Sapphires in the World!


FACTS & HISTORY:
One of the most popular attractions of the Philipsburg area is the sapphire mining offered to the public. It is pretty unusual that people are able to dig through gravel in search of rare, fine gems, but that is just what is offered in Philipsburg. Year round, sapphire gravel is available for washing, and then if you please, you can watch the sapphires get heat treated and prepared for jewelry. There are several places in Philipsburg where you can find these precious gems. The Sapphire Gallery and
Gem Mountain mine located 22 miles from Philipsburg heat treat and cut these wonderfull stones.

Other Montana sapphire localities are located on the Missouri River about 15 miles NE of Helena. If you look at a Highway map you will see Canyon Ferry Dam east of Helena, and just to the west of it is Hauser Lake. Spokane Bar is on the south side, west of the Dam and Eldorado Bar is NW of that on the north side of the lake/river.


Links to digging sites:
http://www.ohwy.com/mt/e/eldosami.htm