A gorgeous cluster of dogtooth spar (scalenohedral) Calcite crystals that are snow-white in coloration and sharp terminations. 

Between 138 and 127 million years ago, the molten rock that hosts the "geodes" overran the local area and in doing so covered older, permeable sandstones bearing artesian ground water, i.e. artesian springs. Fresh, hot basalt lava is a lot like cake batter - somewhat porous, and the superheated steam generated by the contact of hot lava and lots of spring water leached minerals such as Silica and Calcite from the lower portions of the flow and, as these moved upwards under pressure, they finally cooled below boiling water temperature and started to drop their load of dissolved minerals in the only open spaces available: gas bubbles in the lava that ultimately became the mineral lined "geodes" of today. 

9.5 x 6 inches, 3.5 inches tall

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