Radial pyroxene chondrule
A radial pyroxene chondrule has thin pyroxene crystals fanning out from one or more points, like the spokes of a wheel.
A radial pyroxene chondrule is made of slender pyroxene crystals that radiate from a point, usually near the chondrule's edge, spreading across it like a fan or the ribs of an open umbrella. The crystals are often so thin that the chondrule looks finely striped.
This texture forms when a droplet is completely melted, losing all seed crystals, and then cools rapidly. Crystals start growing from a single spot, perhaps where the droplet was touched by a dust grain, and race across the liquid. Experiments reproduce the texture with fast cooling of fully molten drops.
Radial pyroxene chondrules are a minority, typically under about 10 per cent of chondrules in ordinary chondrites. Because they melted completely, they tell scientists that chondrule-forming events were sometimes hot enough to erase all trace of the original dust. Under crossed polars, they show sweeping fans of grey and colour that turn as the microscope stage rotates.
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