Danny looked at his son, Sterlen, for a moment. He didn't sigh but you could tell he wanted to. Well, the thing was, novaculite didn't really correspond to grit size. Grit size was something used to grade manmade stones. And even the people who made manmade stones and went by grit size didn't always agree on what grit size a certain grit actually was. And novaculite was really about the little crystalline structures suspended inside the matrix of the stone. And it wasn't even about the size of those crystalline structures - which were all between 3 and 5 microns - suspended in the matrix that accounted for the different grades of stone. It was, instead, how closely spaced those suckers were, the specific gravity of the stone. Another thing that confused people was the color of the stone. It didn't really mean anything. He had 500 acres of novaculite quarry and mineral rights and only used the best quality stone, which was 99.89 percent pure novaculite. It was just trace elements of other minerals - boron, manganese, aluminum - that accounted for differences in color. I nodded again. I was afraid by this time that they were going to think I was a heroin addict, what with all this nodding. And, to tell the truth, I was beginning to wonder if this more or less permanent state of hiding your confusion was what being a heroin addict felt like.