Ellensburg Blue Agate

WHAT IS IT?

  • A form of Chalcedony (silicon dioxide with very small crystals, i.e. cryptocrystalline)

  • Consists of compact submicroscopic fibrous crystal aggregates

  • Moh hardness: 76 to 8.3

CHARACTERISTICS

  • Gem quality specimens have a lavender sheen when held up to the light

  • Coloring varies from light sky blue to cornflower blue to an almost purple royal blue

  • May contain banding, streaks, or clouds

  • Varies from nearly opaque to transparent

  • The blue color is not caused by impurities (although some may be present), but is caused by light scattering due to voids between Individual crystals

HISTORY

  • It was first discovered by the Kittitas Indians who suggested that one should 'Walk with the sun over your left shoulder" to find them.

WHERE IS IT FOUND?

  • Found in amygdales (filled gas bubbles) in the Teanaway basalt (reddish-colored) formation (Miocene to Eocene, 39 to 47 Mya)

  • Found between Thorp and Ellensburg along the Yakima River and its tributaries and on hillsides

  • A similar blue agate deposit has been found in BC

  • Most (96%) of the agate beds are on private property.  Many of the original beds are in cultivation making hunting impossible.

WHAT IS IT USED FOR?

  • Native American tribes used Ellensburg Blue to make arrowheads

  • Collecting

  • Jewelry