Petrography lower if wholly or partly vitreous. The specific gravity of the more common rocks range from about 2.5 to 3.2. Archaeologists use petrography to identify mineral components in pottery. This information ties the artifacts to geological areas where the raw materials for the pottery were obtained. In addition to clay, potters often used rock fragments, usually called "temper" or "aplastics", to modify the clay's properties. The geological information obtained from the pottery components provides insight into how potters selected and used local and non-local resources. Archaeologists are able to determine whether pottery found in a particular location was locally produced
What Is the What "we really hadn’t decided whether I was just helping Valentino write his own book, or if I was writing a book about him." Valentino points out that, "I thought I might want to write my own book, but I learned that I was not ready to do this. I was still taking classes in basic writing at Georgia Perimeter College." Dave Eggers discusses the difficulties in writing a book of this nature: "For a long while there, we continued doing interviews, and I gathered the material. But all along, I really didn’t know exactly what form it would finally take—whether