About
Dolomite forms in a different crystal class, differing from the Calcite group minerals. This can be noted by the fact that Dolomite generally forms more elongated crystals than those of the Calcite group. In addition, Dolomite never occurs in scalenohedral crystals, whereas minerals of the Calcite group do.
Dolomite is used to describe both a mineral and a rock. The mineral is the pure form with a defined crystal structure and chemical formula, whereas dolomite rock is composed chiefly of the mineral Dolomite, but also contains impurities such as Calcite, Quartz, and feldspar.
Crystal Forms & Aggregates
Other ID Marks
Complex Tests
Striking Features
Environment
Varieties
✓ common · ✗ uncommon
- Cobaltian Dolomite— Hot-pink, cobalt-rich variety of Dolomite.
- Dolomite Rock— Rock composed mostly of the mineral Dolomite, but also contains impurities such as Calcite, Quartz, and Feldspar.
- Pearl Spar— Grouping of white to pinkish curved Dolomite crystals with a pearly luster.
Uses
Dolomite specimens from the the Midwest localities in the Tri-State region of Oklahoma, Missouri, and Kansas are popular collector items. The clear transparent specimens from Spain and the hot-pink variety from the Congo make rare and unusual specimens that are highly sought after by collectors. Dolomite rock is used as an ornamental and structural stone, and for extracting certain metals from their ores.
Noteworthy Localities
The most prominent European Dolomite occurrence is Eugui, Navarra, Spain, where water-clear, transparent crystals uniuque to this occurrence were found in fairly large crystal sizes. Other European localities include the Traversella, Piedmont, Italy; Binn Tal, Wallis, Switzerland; Oberdorf an der Laming, Styria, Austria; the Castilla quarry, Setiles, Spain; and Kapnik, Maramures Co., Romania.
Two important African deposits, famous among collectors for the hot-pink cobalt-rich Dolomite, are Kolwezi, Katanga (Shaba), Congo (Zaire); and Bou Azzer, Morocco. Tsumeb, Namibia, was an outstanding producer of specimen-grade Dolomite, especially of the green, copper-rich type. Other rich worldwide deposits are the Shangbao mine, Hunan Province, China; Brumado, Bahia, Brazil; and Santa Eulalia, Chihuahua, Mexico.
The best U.S. occurrences of Dolomite are in the tri-state mining district of Missouri, Kansas, and Oklahoma, especially the localities of Picher and Joplin, Ottawa Co., Oklahoma, where curved groups of lustrous pink, peach, and white crystals occurred with Galena, Sphalerite, and Chalcopyrite. Two other good Midwest localities are Black Rock, Lawrence Co., Arkansas; and the Sweetwater Mine, Reynolds Co., Missouri. Dolomite was also found in Pennsylvania in the Binkley-Ober Quarry, Manheim, Lancaster Co.
A large dolomite body extends southwest of Lake Ontario in Ontario, Canada, and crosses into the New York border at the Niagara Falls area. It runs several hundred miles through central New York. Several dolomite and limestone quarries in this area have produced nice Dolomite crystals. These include the following New York quarries: the LaFarge Quarry, Lockport, Niagara Co., New York; the Penfield Quarry, Penfield, Monroe Co.; the Walworth Quarry, Walworth, Wayne Co.; and the Herkimer Diamond mining localities. In Canada, this dolomite zone has produced nice crystals at the Canal Dump in Niagara Falls, Ontario. Mont Saint-Hilaire, Quebec, has produced Dolomite in the form of unusual green crystal clusters.
Common Mineral Associations
Distinguishing Similar Minerals
Aragonite - Lacks the cleavage of Dolomite, crystals not curved.
Quartz - Much harder.
Gypsum - Much softer, is sectile and slightly flexible.
Anhydrite - Different cleavage, does not effervesce.
Magnesite - Massive and fine-grained specimens cannot be distinguished from Dolomite by ordinary methods.
Photos
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