2,619. What Can Be Used to Cover

Hilchos Shechita 14:11

Blood can be covered with earth, lime, gypsum, fine manure, fine sand that a potter wouldn’t have to break apart, the erosion of stones and earthenware, thin flaxen chips, fine saw dust, bricks, clay soil and sealing clay that is crushed, because all of these are forms of earth. If one covers blood with a utensil or with stones, it isn’t covered for purposes of this obligation because the Torah specifies “with earth.”

Hilchos Shechita 14:12

Pursuant to the previous halacha, we don’t cover blood with coarse manure, coarse sand, flour, bran, coarse bran or the shavings of metal utensils, because these are not forms of earth. The exception is that gold filings can be used because they’re considered dust, as per Job 28:6 – “the dust of gold” – and Deuteronomy 9:21 – “until it (i.e., the golden calf) was fine, into dust.”