The Embrace (of Ocean Jasper)

The Embrace (of Ocean Jasper)

by Bernardo Cesare, Department of Geosciences, University of Padova, Padova, Italy

View of a thin section of the semi-precious stone called “Ocean Jasper”, a variety found only in Madagascar.
Being mined out, Ocean Jasper 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.
I have long been searching for affordable samples of Ocean Jasper, until I saw a necklace in a market stall. I cut all the beads (with some disappointment from my wife), prepared thin sections from them, and put them under the microscope: they turned out to contain a microscopic garden of flowers of quartz in a fine-grained silica matrix.
In this view, a "rosette-shaped" cluster of coarser, more crystalline quartz, surrounded by aggregates of finer, fibrous chalcedony, mimicks an embracing couple.
Polarized light photomicrograph. Width of view 5.3 mm