Rockhounding Utah For Blue Agates Formed in a Calcite Host

The mountains surrounding the small town of Central, Utah are a great place to rockhound. There, Shadow and I search for and find beautiful blue agates. Unlike many agates we have found in Southern Utah, these agates were formed in a calcite host as opposed to a volcanic host. Agates form when geothermal activity washes water mixed with Silica into the cavities of a host rock. Over many years, layers of silica harden under heat and pressure into what is commonly called calcedony. An agate is a member of the calcedony family and is translucent or transparent, and often shows banding. These agates are just that: translucent or transparent with signs of banding. Shadow and I have been here rockhounding before and have gathered and polished some samples. At the end of the video we show these previously tumbled and polished samples.

At the end of the video, we also test the rocks we gathered using a Mohs Hardness Test Kit and Hydrochloric Acid. The agates tested at 7.5 on the Mohs scale. The calcite host tested softer than 3. We proved the host was calcite based by applying hydrochloric acid and observing the effervescent reaction.

Rockhounding is a wonderful hobby. I am an amateur. I have learned much over the years, but continue to learn more from others who post informative videos on youtube, from many excellent books, and from gaining more experience. Shadow and I hope you enjoy coming along with us. We invite you to come along on future Adventures of Shadow.