It has been found in deposits from hot springs and fumaroles such as on Mt. Vesuvius, Italy. Epsomite forms large sedimentary beds having been included in some very unusual marine salt deposits in South Africa. As might be expected, large crystals are few. Crusts and massive forms are more common. Some of the best specimens have attractive fibrous almost cotton-like aggregates with a silky luster.
Identification is usually pretty easy.
Besides the easy solubility, the taste is very diagnostic. If you have ever tasted epsom salt, you have tasted epsomite and know of the bitter taste. The easy solubility is a detriment to most specimens in collections. To keep epsomite it is recommended to clean the specimens gently with alcohol and then store them in sealed containers. O. It is perhaps hard to believe that the loss of one molecule of water can make a new mineral, but in this case the water molecules are intricately involved with the structure of epsomite.