On the trail back from the crater, a large complex of shallow cement ponds can be seen. Contrary to expectations, these are not evaporation ponds but warming ponds.
These ponds formed part of hte soda and salt factory that operated at Tswaing from 1912 to 1956. They were probably built during the early 1930's and used on the production of salt. Although the crater is known as a "salt pan", it was exploited mainly as a source of soda since mining operations began in 1912. For many years salt was produced irregularly and in small quantities. Salty liquid from the crater lake was first pumped to the soda factory where it was cooled to a tempreature of -10 degrees Celcius. Here soda was extracted from the liquid. The remaining liquid was pumped to these ponds, where it was stored and allowed to warm up to air tempreature. The warm liquid was pumped to the salt factory where it was filtered, boiled and evaporated in order to extract the salt. The bags of salt and soda-ash were taken by ox wagons (later motor trucks) to Hammanskraal Station, 22 kilometres east of Tswaing. From there these products were transported by train to various destinations in South Africa.
Source: Tswaing Mereorite Crater Booklet - available at the Tswaing office.
PLEASE NOTE: There is a small entrance fee of R20.00 per person payable if you enter Tswaing Meteorite Crater.