Description Agate – Zebra Tumbled Stones have a Trigonal crystal system and is in the mineral class of oxides, the quartz group. I should mention that some may know this one as Crazy Lace. It is a unique combination of Quartz and Basalt (volcanic rock). Hot silicic acid solutions accumulate in hollow spaces from gas bubbles in cooling lava. As they cool, they solidify into quartz, layer by layer, in these hollow spaces. Its coloring is always black and white, and generally in a noticeable striped “Zebra” pattern. Occasionally small amounts of iron have been encompased by the quartz and they may show fine red to brown colored lines between the Quartz and Basalt unions, but more often it is just Quartz and Basalt.
