Tube Agate 925 Silver Pendant

100% natural, artisan-mined Tube Agate hand-cut and set in 925 Silver by Eric Cifani in Las Vegas USA. Tube agates are formed in the earth's crust by a sequence of complex geological processes in which siliceous tubular structures form in volcanic provinces. Gas bubbles are trapped within cooling flows of lava. Over tens of millions of years, these bubbles gain their hollow voids. Silica-laden hydrothermal fluids fill these voids and then start depositing layers of mostly quartz or chalcedony. The tubes often remain hollow or are sometimes subsequently filled with other minerals. Different filling stages with different minerals deposited in a sequence give some of the tubes a banded or multicolored look as distinct layers of various colors are added to their walls. This is an exceptional Tube Agate specimen. Size: 40mm x 30mm / Weight: 12.5gm. Includes: Gift Box & Leather Necklace, silver chain shown NOT included.