A fantastic quartz crystal cluster from Arkansas that has a small rainbow. This very beautiful cluster is called a square back because it formed on top of a calcite bed, which later weathered out leaving square cavities on the bottom. The very light yellow tint at the base is due to included limonite. Stands up on its own. Size: 3 3/4" long x 2 5/8" wide x 2 1/8" tall.