Ferrous sulfate (copperas or iron sulfate) in loose, greenish or yellow-brown, odorless crystals. Soluble in water, insoluble in alcohol. Uses include sewage treatment, fertilizers, feed additives, reducing agent, wood preservatives and process engraving.
Used in the following patina formulas:
Ferrous sulfate readily forms pale, blue-green, triclinic crystals. Read our article, "Growing Large Crystals with Seed Crystals" for more information.