Description
Halite is a water soluble material composed of sodium and chlorine ions. Pure halite appears colorless or white but may appear tinted with yellow, red, pink, blue or purple when impurities are present. Halite has a salty taste, low hardness, breaks apart in the presence of moisture and has a high melting point.  Halite is an indispensable seasoning in everyday foods. It can also be used to extract sodium and chlorine for making hydrochloric acid and other compounds, making it a very important raw material in the chemical industries. Depending on the source, halite can be classified as rock salt, sea salt, lake salt or well salt. In Taiwan all salt production comes from seawater, with sun evaporation and electrolysis with ion exchange membranes the main methods used. In recent years Taiwan has imported around 300,000 tonnes of industrial salt from Australia every year. Food-quality salt is produced by the Tongsiao Salt Factory with annual production around 100,000 tonnes.

Mineral Formation
(1) From the evaporation of seawater (Image 1).
(2) Manufactured using the electrolysis with ion exchange membranes method at the Tongsiao Salt Factory.

Geographic Distribution
(1) The salt fields are mainly found along Taiwan's southwest coast in Tainan County, Chiayi County and Kaohsiung County.
(2) The Salt Factory at Tongsiao in Miaoli County.
 
Mining History
The earliest salt production in Taiwan was through the boiling of seawater. The salt field method was introduced from China by Chen Yong-hua in 1665 with the construction of the Laikou Salt field in Tainan.

In 1919 the Japanese set up the "Taiwan Salt Making Company" and embarked on an aggressive expansion of salt fields to supply domestic demand in Japan. The "Taiwan Salt Works" was established in 1952, nationalizing the production of salt. Rapid industrial development in Taiwan during the 1960's led to a high demand for industrial salt so extensive expansion and upgrading of the salt fields with new equipment and techniques occurred. The addition of iodine to salt was also implemented at this time. The Electrolytic Salt Factory was constructed at Tongsiao Township in Miaoli in 1975 for the production of food-quality salt, ensuring that weather was no longer a factor in salt making. During the 1980's the focus was on modernizing the salt industry and replacing manpower with machinery to reduce costs and boost production. The problem of frequent rainfalls in the summer however meant the Taiwanese salt fields could not compete against foreign competitors in terms of cost and volume so the salt fields started closing down one by one. Taiwan Salt Works was restructured as "Taiyen" in 1995. A joint venture was set up with the Dampier salt company in Australia to develop new salt fields with the product sold back to Taiwan. The Cigu Salt Field ceased production in 2002 and this marked the end of 338 years of solar salt production in Taiwan. Taiyen was privatized in 2003 and the salt monopoly abolished so foreign salt products could be imported to Taiwan. Today, all of Taiyen's industrial salt is sourced from Australia (Image 2, 3 and 4) with around 300,000 tonnes imported each year. Food-quality salt is produced domestically at the Tongsiao Salt Factory with annual production of around 100,000 tones. 

Production
In 1952 the salt fields produced 308,940 tonnes of salt. In 1971 salt production at the salt fields peaked at 603,123 tonnes.

Refined salt production in 2005 was 76,284 tonnes and washed salt production was 38,105 tonnes. Refined salt production in 2006 was 73,849 tonnes and washed salt production was 33,864 tonnes. 
(Note) Salt evaporation is where seawater is used to fill salt fields and then evaporates under the sun (Image 5). Refined salt is produced by concentrating seawater into brine then letting it evaporate and crystallize; washed salt is produced by crushing raw salt then washing it with saturated brine to remove impurities. 

 Applications
(1) Used as a seasoning and preservative
(2) Used as a raw material in the chemical industries for producing soda, hydrochloric acid and metallic sodium.
 
Tongsiao Salt Factory
The Taiyen Salt Factory was built at Tongsiao in Miaoli County in 1975 because it was next to the Taiwan Strait, free from industrial pollution and with good transportation access. Seawater is used as the raw material and salt is produced using the electrolysis with ion exchange membranes process. Production is completely automated. This method of salt production is immune to weather effects and is able to produce high-grade refined salt on a consistent basis. It also requires less land and manpower, though it does consume large amounts of heat and electricity. Machinery is also a very significant investment. The Tongsiao Salt Factory is the only local producer of salt in Taiwan. The 100,000 tonnes of salt produced each year mainly goes towards meeting the demand for edible salt in Taiwan. 
 
Taiwan Salt Museum
In 1998 Taiyen began planning work on the "Taiwan Salt Museum" to commemorate 338 years of salt industry history in Taiwan. The Museum was officially opened in Tainan County at Cigu Township in 2005. The first floor of the Museum uses salt evaporation machinery, models and pictures to bring the old salt fields of Taiwan to life. There is also a Salt Village theater and audio-video room. The second floor of the Museum features the "Taiwan Salt" and "Children's Place" exhibits. Taiwan Salt provides a detailed overview of more than three centuries of salt field history in Taiwan. In the Children's Place there are mini-games to teach children salt knowledge; the fourth floor looks at the salt industries of the world including models of the salt mines in Poland and salt wells in Sichuan. There is also a "Salt and Science" exhibit that explains salt formation, crystallization, applications (Image 6) and related trivia. 
 

National Museum of Natural Science