What is the structure of a thiosulfate ion?

The structure of a thiosulfate anion is a slightly distorted tetrahedral shape in which the central atom is sulfur with three surrounding oxygen atoms and a second peripheral sulfur atom. The ion is very similar to a sulfate ion.

Thiosulfate ions are formed when sulfate ions interact with elemental sulfur or when sulfides are partially oxidized. This reaction requires a lot of heat and typically only occurs in boiling water. As a result, thiosulfates are typically found in and near hot springs and geysers. Thiosulfate has industrial uses as a reducing agent and is frequently used in the production of silver and in photo processing.