For April we did a 2-day trip to Central and SE WA. We were really blessed with gorgeous weather both days. On Sat April 23rd we went to Saddle Mtn for petrified wood. We met in Mattawa for the trek up the bumpy Saddle Mtn road. 11 vehicles and 20 people. There was another group on the ridge where we went, but it’s such a wide area with lots of pits so it wasn’t a problem. Within the first 15 minutes of digging, I found the nicest piece of petrified wood I’ve ever uncovered there. The rest of the day I found a few nice smaller pieces, and everyone was finding nice material. Afterwards, a few of us went to the diatom pits at Beverly for opal. Found some beautiful pieces there and a renewed curiosity for how they formed.
I had to refresh my memory on the differences between agate and opal, because some of the petrified wood is agatized and some is opalized, and the diatom pit opal can be as nice as agate in appearance. So here’s a quick study. Numbers vary slightly depending on the source of information.
Agate/Jasper/Quartz are a structure of tiny crystals with a Moh’s hardness of 7-7.5 and a specific gravity (density) of about 2.6. Opal is a structure of tiny spheres with a Moh’s hardness of 5.5-6 and a specific gravity of about 2-2.25. Opal also has more water content. Both are formed from mineral rich water (silica + other minerals) seeping into the ground or bedrock and settling in cracks or pockets. Variations in climate, heat, pressure, rainfall, mineral content, etc., add to the variations found in the rocks we collect. That’s a condensed version of what I read today.
Attendees: Peggy S. and Paul, Kamera M., Kelly and Tim B., Olga A. and family, Nik B., Mike B. Loren M., Ashley E. and family (guests), John and Dave C., Sara (guest), and me.
Part 2 of our April weekend was at Fir Road north of Pasco on April 24th. I’ve been watching social media posts of Carnelian being found there and I wanted to check it out. Due to the distance, I thought it would be good to combine it with the Saddle Mtn. trip. We stayed at various hotels and campgrounds in the Tri-Cities area. Fir Road is about 18 miles north of Pasco and contains an immense wall of river rock next to the Columbia River. I’m guessing related to the glacial floods that impacted central WA. Our experience was that Carnelian was hard to come by, though a few pieces were found by the group. But there is a lot of quartz and quartzite type rocks that will tumble and polish nicely. Many having well defined layered lines, similar to agates, but I think it’s a grey area. I suspect sedimentary and metamorphism. Agates and jasper should be microcrystalline and very glass like, but most of these when broken open have visible crystal structures (quartz and quartzite). I wouldn’t recommend a special trip over just for this site, but I think it’s a good spot if you’re in the area and desire tumbling material. Pasco is 225 miles from Kent/Renton. We certainly had fun and enjoyed the weather.
Attendees: Peggy S. and Paul, Kate T. and family, Kamera M., Phillip T., Kelly and Tim B., Olga A. and family, Nik B., Joye E. and family (new member from the Tri-Cities), Mike B. Robert M. and family, John and Dave C., and me.
Submitted by Roger Danneman Field Trip Guide (roger.danneman@gmail.com)
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