Question: what are epsom salt crystals?
Answer: Epsom Salt Crystal Materials Epsom salt is another name for magnesium sulfate (MgSO4), but the crystals incorporate water to form magnesium sulfate heptahydrate (MgSO4·7H2O). Epsom salt is an inexpensive, non-toxic salt that is readily available in pharmacies for bath salt and agriculture stores as a soil treatment.