The Mineralogical Society of Southern California

Program Notes: Friday, August 8, 2025  at 7:30, join us for Sakura Ishi (Cherry blossom stones) from Kyoto, Japan: Mica pseudomorphs of complex cordierite – indialite intergrowths” Presented by Dr. John Rakovan

Cherry blossoms have been revered for more than a millennium in Japan and have become one of its most recognized icons. In the city of Kameoka, Kyoto Prefecture, one can find mica pseudomorphs after complex cordierite-indialite intergrowths. These remarkable pseudomorphs resemble cherry blossoms and are known locally as sakura ishi, which means cherry blossom stone in Japanese. As with the real cherry blossoms, sakura ishi are also revered by mineralogists and mineral collectors in Japan. The cordierite-indialite precursors to these pseudomorphs are only found in this unusual intergrowth in central Japan, mostly in Kyoto Prefecture. To understand how sakura ishi form it is necessary to look at the unaltered cordierite-indialite precursors. These can be found elsewhere in Kyoto, including Daimanji, one of the most famous mountains in that city. The formation history of these unusual crystals includes segregated epitaxic growth of cordierite on indialite, metastable crystal growth, transformation of indialite to cordierite and finally pseudo-morphic replacement by mica. This talk will cover the interesting mineralogical phenomena involved in the formation of intriguing mineral specimens.

Dr. John Rakovan is the state mineralogist and senior museum curator of the New Mexico Mineral Museum at the New Mexico Bureau of Geology and Mineral Resources. He has been an executive editor of and regular contributor to Rocks & Minerals magazine since 2001 and was a professor of mineralogy at Miami University for 25 years. John has broad research interests including crystal growth, structural and morphologic crystallography, and mineral deposit formation.