Some geologists are uncomfortable using the word “dolomite” for both a mineral and a rock of the same composition. They instead prefer using “dolomite rock” or “dolostone” when speaking of the sedimentary rock and “dolomite” when speaking of the mineral. Although these terms simplify communication and improve accuracy, many geologists continue to use the word “dolomite” for both the mineral and the rock.
Dolostone: Photograph of a specimen of the Little Falls Dolostone from Herkimer County, New York. This dolostone is the host rock for the doubly-terminated quartz crystals known as “Herkimer Diamonds.” It is vuggy, has a high silica content, and is much harder and tougher than the typical dolomite. The Herkimer Diamonds are found in petroleum-lined vugs in the rock unit. Part of a Herkimer Diamond is visible in the large vug on the left side of this specimen.
