This vibrant blue crystal in my neon gloved palm is derived from the Greek words, chalkos, and anthos–meaning copper flower. Chalcanthite is a water-soluble sulfate mineral. This means that it will melt in water–and due to its high concentration of copper, it is highly toxic in this form.
Chalcanthite is also a type of hydrated called a pentahydrate. Hydrates are inorganic salts that have water molecules combined in a definite ratio as an integral part of the crystal. These are often bound to a metal center or have crystallized with the metal complex. These also have water hydration or crystallization.
Forbes, on its list of the 9 deadliest rocks and minerals on the planet, noted that Chalcanthite is used to ore copper and that the water solubility of this mineral can easily lead to copper poisoning of an environment and is toxic to humans.
The Science Explorer points out that since it is water-soluble, it can be absorbed in large quantities by any plant, animal or human. It will weaken and kill whatever absorbs it by shutting down essential body processes. Also, it should never be tasted to test for salt content due to its toxicity.