U.S. Borax Mine, Kramer Borate deposit, Boron, Kramer District, Kern Co., California, USA
Lustrous, blocky crystal of yellow Calcite to 19 x 11 x 6 mm, and spires made up of flat blades of light-yellow Calcite, make up this specimen. The blocky Calcite shows pronounced striations and tiny acicular features on its surface. Small amounts of Ulexite are also present. This is an excellent and rare example of a near complete replacement of Ulexite by Calcite from Boron.
ex. Marty Houhoulis (Denver) collection