Description Agate – Blue Lace Tumbled Stones have a Trigonal crystal system and is in the mineral class of oxide, the quartz group. Its coloring is pale blue with lighter, sometimes almost white, lacy patterns and bands. Agates are formed hydrothermally in silicic acid-poor volcanic rock. The hot silicic acid solutions accumulate in hollow spaces formed by gas bubbles in cooling lava. As the solutions cool, they solidify into a quartz mix, deposited layer by layer on the walls of the hollow spaces. Its banding is made of the most varied combinations of crystal quartz, chalcedony and jaspers. Whenever the agate fills an entire hollow, it is called an “agate almond”. If a hollow remains in the center, it is called an “agate geode”.
