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New Mexico Mineral Symposium — Abstracts

"Sakura Ishi" From Kameoka, Japan: Mica pseudomorphs of complex cordierite - indialite intergrowths

John Rakovan

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Cherry blossoms have been revered for more than ten centuries in Japan and have become one of its most recognized icons. In the city of Kameoka, adjacent to Kyoto, mica pseudomorphs after complex cordierite-indialite intergrowths are found. 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. Kyoto has been the cultural center of Japan for a millennia, and it is fortuitous that this mineral would be from a place so intimately associated with an admiration for cherry blossoms. If the Japanese were inclined to name prefectureal minerals, as state minerals are named in the U.S., then sakura ishi would be the obvious choice for Kyoto.

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 formational history of these unusual crystals includes segregated epitaxic growth of cordierite on indialite, transformation of indialite to cordierite and finally pseudo-morphic replacement by mica. An article on the origin of sakura ishi was recently published in Rocks & Minerals (2006), (v. 81, no. 4], pp. 284-292.

Figure1: Sakura ishi (cherry blossom sonte), from Kameoka, Japan
pp. 14

28th Annual New Mexico Mineral Symposium
November 10-11, 2007, Socorro, NM
Print ISSN: 2836-7294
Online ISSN: 2836-7308