CuSO4 ranges in color from grayish white in powder form to bright blue in crystal form. Because of the crystal color, CuSO4 is sometimes called bluestone.
CuSO4, or copper sulfate, is a salt that is commonly used in pesticides, herbicides, algicides and fungicides. It is safe when handled properly but can be poisonous if ingested orally, according to the National Pesticide Information Center. Copper sulfate may cause itchiness or a rash when in contact with skin.
Copper sulfate occurs naturally very rarely but is more commonly man-made. The largest crystal of copper sulfate ever recorded was 153.88 pounds. It was grown by German students.