Barite Gems, Roses, and Crystals

Mine Hills blue barite gems, Shirley Basin, Wyoming (Hausel, 2014). These gemstones form
excellent, transparent blue, orthorhombic prisms with two directions of perfect cleavage, and
one imperfect cleavage. These make stunning specimens in mineral collections, but for some 
reason, these still remain untouched for manufacturing gemstones and jewelry.

Barite (BaSO4) (barium-sulfate), when found in crystalline form, may occur as attractive mineral specimens that will enhance any mineral collector’s or rock hound’s collection. Such crystals are considered principally industrial minerals and have a relatively low Moh’s hardness of 3 to 3.5, which means you can easily scratch it with a pocketknife. 

Most unusual is its relatively-high specific gravity (sg = 4.5) for a non-metallic mineral. It is high enough that one of the post important physical properties used to identify barite in the field, is its heft. After you return home, to your lab, or office, then you can confirm its specific gravity if necessary.

Blue barite, Mine Hills, Shirley Basin, Wyoming
(Hausel collection). These are some of the better
specimens found in the world, but remain to be
faceted into gemstones.

Density relates to mass per unit volume. The specific gravity is its relative density (weight of the mineral divided by the weight of an equal volume of water). Its high specific gravity produces noticeable heft, which aids in identification of barite. Heft is a relative measure of a minerals specific gravity, so that when you bounce a hand specimen in the palm of your hand, it will seem unusually heavy for size.

Barite is usually found as concretions or void-filling crystals in faults, fractures and in sedimentary rocks. It often occurs as concretions and veins in limestone, dolomite, and even sandstone. Wherever these rocks crop out on hill- or mountain-sides, erosional debris will accumulate at the base of the outcrop, potentially yielding a residual concretion deposit in soil and alluvium downslope from the rock.  

Barite may also occur in sand and sandstone. In some cases, concretions formed by crystallization of barite within interstitial spaces in sand or sandstone produce classical barite roses. And wherever fractures tap hot springs; sometimes barite, metallic sulfides, calcite and/or quartz are carried in hydrothermal fluids, and precipitate in fractures and faults.

When found in large tonnages in massive form, or as residual deposits, it may be mined and used in a number of different applications including drilling mud additive to aid in blowout prevention in oil and gas exploration due to its high specific gravity. 

Massive, fracture-fill barite, Laramie Mountains, Wyoming.

Barite crystallizes in the orthorhombic crystal system and exhibits tabular crystal habits parallel to the crystal base. Other habits include fibrous, nodular, massive and aggregates or divergent groups of tabular barite crystals. Barite exhibits perfect cleavage parallel to the base and prism faces. Minerals are often colorless, white, yellow, grey, brown and less commonly light shades of blue. Crystals are brittle, produce irregular fractures, and have vitreous to pearly luster. 

Barite is rarely used as gemstones, but some transparent, colored, specimens yield very attractive stones when faceted. However, because perfect cleavage and relative softness, the gemstone should be protected by jewelry mounts: daily wear is not recommended as it will easily scratch. Some of the more attractive blue barite in North America is found in the Mine Hills area of the Shirley Basin of Wyoming. Many crystals in this area are transparent and have pleasing, blue color; but, as far as the author is aware, these potential gems remain untapped for jewelry.

Crystals exhibit distinct right angle prismatic cleavage. Tabular white, yellow, grey, blue, red, or brown, opaque, translucent and transparent crystals have been reported.

Some of the more attractive specimens found in Wyoming are light aquamarine blue, transparent to translucent, thin tabular crystals compressed along the c-crystallographic axis. This compression produces distinctly large crystal faces. Individual crystals of the Wyoming aquamarine blue barite, occur as plates with distinct beveled edges. Perfect basal cleavage parallel to the c-axis lies perpendicular to imperfect prismatic cleavage parallel to the b-axis. Where found near the Mine Hills the Shirley Basin of southeastern Wyoming, the barite is in vugs in limestone enclosed by calcite and rarely prismatic quartz.

Wyoming Localities

Shoshone Canyon (SE section 5, T52N, R102W). Small radial clusters of white barite crystals are found in the Shoshone Canyon area of Rattlesnake Mountain, 4 miles west of Cody in northwestern Wyoming. Some crystals from in this area are reported to be one inch in length. This barite is associated with paleo-hot spring deposits and solution cavities in the Mississippian Madison Limestone.

New Rambler mine (SW section 33, T15N, R79W). Fine-grained to massive pyrite was reported with barite at the New Rambler copper-gold-palladium-platinum mine in the Medicine Bow Mountains west of the Rob Roy Reservoir.

Fault-fill, quartz breccia with barite, Hog Park, Medicine Bow
Mountains, Wyoming (Hausel collection).

Hog Park (NW section 2, T12N, R85W). A pod-like mass of barite, 40 feet wide by 300 feet long, was described to be associated with opal in the Hog Park area of the Sierra Madre Mountains several miles southwest of Encampment. The barite is found  along the northern edge of a shear zone in contact with pink to red quartz monzonite. When investigated by the author, no evidence of opal was found; but, white crystalline to massive barite was present.

Shirley Basin. White barite concretions are found in Shirley Basin northeast of the town of Medicine Bow. These are weakly fluorescent under long-wavelength ultraviolet light.

In addition to white barite, very attractive aquamarine blue barite crystals occur in the vicinity of Sheep Creek near Crystal Hill adjacent to the Mine Hills (section 10, T26N, R75W) along the southeastern margin of the basin and adjacent to the western flank of the Laramie Range. Mine Hills is situated on the Laramie Peak 1:100,000 topographic map and are accessed from the west from Shirley Basin (see also Shirley Basin 1:100,000).

The barite occurs as attractive light-blue, transparent to translucent, tabular crystals and is found with calcite and quartz in vugs in the Casper Formation near a massive psilomelane, manganite (manganese) and jasper replacements in the Casper Formation (Hausel, 2014; Hausel and Sutherland, 2000).

Mine Hills, vug-fill, blue barite, Shirley Basin, Wyoming. Note the crystal habit of these perfect,
tabular blue crystals with beveled edges (Hausel collection).

References

Dana, E.S., and Ford, W.E., 1949, A textbook of Mineralogy: John Wiley & Sons, 851 p.

Hausel, W.D., 2014, A Guide to Finding Gemstones, Gold, Minerals and Rocks: CreateSpace, 368 p. 

Hausel, W.D., and Sutherland, W.M., 2000, Gemstones and other unique minerals and rocks of Wyoming: Wyoming Geological Survey Bulletin, 267 p.

Sinkankas, J., 1964, Mineralogy: Van Nostrand Company, 585 p.