It is found as a mixed iron(III) aluminium sulfate. This is the anhydrous form. Several hydrated forms are found, too. Much more iron(III) sulfate is found in Mars. One of the rovers that travel on Mars got stuck in a pit of iron(III) sulfate and could not get out.
It is made by mixing sulfuric acid, iron(II) sulfate, and an oxidizing agent like nitric acid or hydrogen peroxide together. It is made when iron(III) oxide reacts with sulfuric acid. It is also made when iron(II) sulfate is oxidized by exposure to oxygen.
It is used as a mordant in dyeing. It is also used to coagulate waste to remove the toxic parts. It is also used in baths to clean metals. It can be used as a pigment. It is used as an astringent in medicine. It stops bleeding.