Petrography rock was affixed to a microscope slide and then ground so thin that light could be transmitted through mineral grains that otherwise appeared opaque. The position of adjoining grains was not disturbed, thus permitting analysis of rock texture. Thin section petrography became the standard method of rock study. Since textural details contribute greatly to knowledge of the sequence of crystallization of the various mineral constituents in a rock, petrography progressed into petrogenesis and ultimately into petrology. It was in Europe, principally in Germany, that petrography advanced in the last half of the nineteenth century. The macroscopic characters of rocks, those
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