
Ocean Jasper From Madagascar, Lm #13

by Bernardo Cesare
Title
Ocean Jasper From Madagascar, Lm #13
Artist
Bernardo Cesare
Medium
Photograph - Photograph
Description
Polarized light photomicrograph of a thin section of Ocean Jasper, a semiprecious stone mined only in Madagascar. Being mined out, this rock is becoming among the most collectible stones for lapidary. Ocean jasper is characterized by the presence of small spherical aggregates (spherulites or 'orbs'), just a few mm in diameter, that derive from a process of alteration and silicification of former volcanic flows of tuffs or rhyolites. The image shows aggregates of quartz called 'rosettes' set in a matrix of fine-grained quartz called chalcedony. Polarized light, crossed polarizers and red tint plate. The rock slice (thin section) is 30-micron-thick. Zeiss Axioscop 40pol.
Uploaded
July 21st, 2022
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