Hello PIGs: My essay #7 is posted to the PIG website. It pertains to an article by Kuz'ma Vlasov: Vlasov, K.A (1961) Principles of classifying granite pegmatites and their textural-paragenetic types. (In English) Transactions of the Academy of Sciences, U.S.S.R., Geologic Series, 1, 5-20. Vlasov's classification of pegmatites was simple, but not simplistic. It was and remains as the only comprehensive granite-to-pegmatite classification that combined rock texture, which is the defining attribute of pegmatites, with mineralogy and internal zonation. Unlike later classifications that have addressed only those pegmatites that contain rare-element minerals, Vlasov's scheme included pegmatitic granites (his Type I) and the common pegmatites (his Types II and III), which constitute more than 98% of all pegmatites (Cerny, 1991) and consist of "99.9% feldspar, quartz, and mica" (Vlasov, 1961). More important than the types of pegmatites he proposed, his renderings conveyed the regional-scale and spatial changes among consanguineous pegmatites of a group from granitic source to the most distal bodies. His was the first confirmation of zoning trends across a pegmatite group of what has come to be known as the LCT (Li-Cs-Ta) family (Cerny, 1991). He recognized that the so-called albite-spodumene pegmatites, which are now exceedingly important for their large reserves of lithium, may be unrelated to the LCT family in source and environment. Vlasov's professional profile can be seen here: http://mining-enc.com/v/vlasov-kuzma-alekseevich/ His article is posted along with the essay. David London Learn about pegmatites and join the Pegmatite Interest Group at http://www.minsocam.org/msa/Special/Pig/