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 This? following week. The group decided to change their name to the Red Hot Chili Peppers, played several more shows at various L.A. clubs and musical venues, and eventually recorded a demo tape, all while Slovak and Irons were still playing with What Is This?. A few months later, What Is This received a record deal with MCA Records and the Red Hot Chili Peppers received a joint deal with EMI America and Enigma Records. Hillel Slovak and Jack Irons decided to leave the Red Hot Chili Peppers and stay with What Is This? as the latter was their primary musical