Curved
crystals of Dolomite.
Rhombohedral crystals of Dolomite
Classic
pink crystals of Dolomite from the Tri-State mining district near Joplin, Missouri.
A close-up view of the above showing the association of Dolomite with small
crystals of Chalcopyrite. Note also the curved "saddle-shaped"
crystals.
CHEMISTRY CaMg(CO3)2 Calcium magnesium carbonate
CRYSTALLOGRAPHY Hexagonal
CRYSTAL GROWTH AND HABITS Dolomite crystals are typically rhombohedral and are often curved producing "saddle-shaped" crystals. Dolomite can also occur as granular to compact fine grained masses.
COLOR AND OTHER OPTICAL PROPERTIES Dolomite is commonly pinkish but may also be clear, white or gray to black.
HARDNESS 3.5 - 4
SPECIFIC GRAVITY 2.85
LUSTER Dolomite is normally vitreous but can grade into dull in massive varieties.
STREAK White
BREAKABILITY Good rhombohedral cleavage with angles of 73.75o.
OCCURRENCE Found widely as the sedimentary rock dolomite (dolostone). It is also found well crystallized in pockets in limestone and dolomite.
ASSOCIATED MINERALS Calcite, Barite, Galena, Sphalerite, Pyrite and Chalcopyrite
OTHER PROPERTIES When dolomite is powdered it reacts slowly to cold, dilute hydrochloric acid.