Wilson 1½ quot x ¾ quot Railroad Ballast is a clean 100 crushed granite This Ballast isproduced daily at Wilson Thisproduct has been used by the Railroad as Ballast Aggregate since the late 1800 39 s Thistype of rock is typically gray in color in accordance w ASTM C88 4 8 Specific Gravity 2 82 Unit Weight 100 7 lb pcf nbsp