most newbie hunters would really think that the materials that glitters in the rock are gold dust. but if you have it assayed, it is most likely pyrites. pyrites look like gold dust in the front but at the back of it, there is a black color on it. that appearance where it looks like gold in the front but black at the back of it is a physical characteristic of pyrite. pyrites glitters from afar , that is why it is usually mistaken as a gold dust.
pyrites are included in the composition of the cement because it makes the cement harder. there is a mixture of epoxy, very solid and pure mixing of cement, shells and more pyrites. there are other components which only the japanese know. but the point is, most pyrite components are usually mistaken as gold dust, which according to laymen's understanding , can get them huge payday if the amount of gold dusts are consolidated into huge quantities.
but if you dont want to waste your time guessing if it is a gold dust or pyrite, better have it assayed. it will definitely settle your doubt. the lab results will definitely tell you if there are traces of gold dust or none.