Description
Dolomite is the main mineral found in dolostone and dolomitic limestone. Mainly made up of calcium carbonate and magnesium carbonate, it is an important source of magnesium carbonate for Taiwan. Dolomite measures between 3.5 and 4 on the Mohs' hardness scale and has a specific gravity of around 2.8 to 2.9. It is generally colorless or white in color though it appears yellowish or brown if iron is present, or light pink if it contains manganese.
Dolomite is found in eastern Taiwan within the metamorphic crystallized limestone strata in the Tananao Schist from the Tertiary Period. The deposits appear in lens-shaped formations, layers or irregular pockets. 

Mineral Formation
Dolomite is formed when magnesium irons replaces part of the calcium ions in limestone. 

Geographic Distribution
Found in the crystallite limestone and metamorphic rock on the eastern slopes of the Central Range. 

Mining History
Japanese records indicate that Dolomite was found in the riverbeds of eastern Taiwan in 1913. Most of these had been washed down the river before accumulating in the riverbeds. Actual Dolomite deposits were not found until 1931 by Japanese surveyors such as Motosuke Igasaki. The deposits found at the time were relatively few and small in size. The Taiwan Mining Resource Industrial Company (台灣礦業資源工業公司) began mining Dolomite from the riverbeds in 1944 to supply the Taiwanese steel industry, fire-resistant materials industry and construction industry. Operations were concentrated around the Jhihyagan River basin in Hualien County. Dolomite production gradually increased after 1954 when mine operators began venturing deeper into eastern Taiwan. Today, most Dolomite mining is carried out along the Dajhuoshuei River (Heping River) and the Cingchangshan region in Hualien County. 
 
Production
In 1944 annual production of Dolomite was 550 tonnes (J.S. Wei and L.P. Tan, 1999) with production continuing to increase from then on. Dolomite production in 2005 was 173,986 tonnes and in 2006 it was 61,224 tonnes. 
 
Applications
(1) Fire-resistant material.
(2) Metallurgical solvent.
(3) Chemical engineering material.

National Museum of Natural Science