Out of the Tumbler

Beach Cobbles, San Simeon, CA

As I posted back in March, I spent a pretty mind-blowing day collecting on the beaches near San Simeon, California, on my way up the coast. Why was it so great?  Because nearly every rock on the beaches there is of something interesting, whether a brecciated jasper, or an interesting agate, or some things that I don't even know the names for. But whatever they are, they have loads of color and striking patterns and polish beautifully in the tumbler.

They do especially well in the tumbler since they are already well-rounded by the wave action. In fact, I usually skip the first coarse grit step in the polishing process and go directly to the finer 120/220 silicon carbide.

I'm still processing rocks I found months ago, and by the time I'm done, it'll be time to head South again to find some more!

Area 54

Misc. Jasper & Agate, Area 54

Some rockhounding locations are in the guidebooks. Others are not, either by the author's choice, or because they are new locations, found just as others are exhausted by hundreds - if not thousands - of collectors.  This place was not one I'd ever read about, except on a rockhounding club website. I don't know where it got it's name - Area 54 - but it does give the place a sense of mystery: it sounds like there should be aliens or UFO's around.  All I can say is, I didn't see any...

The truth is, I don't know exactly where Area 54 is, or at least where the club trips go. It is somewhere on the road into the Panoche Hills in Fresno County, California. I never found the exact spot they described, but it doesn't matter. You can look anywhere in a 5 mile radius, or anywhere along that road and you will find colorful, sometimes stunning, material. The pieces I've posted here just came out of the tumbler - but I have much more.

My advice?  Next time you're driving south on I-5 in central California, take a short detour and explore this canyon.  You won't be sorry!

FOLLOW-UP NOTE: June 15.  I've finally gotten these stones all the way through the polishing process, and sadly, they don't polish well. Most have a largely matte finish with only a few seams that took a good polish. I might have worried that I had done something wrong in the process (such as contaminating the batch with heavy grit somehow) but there were a few agates from elsewhere in the batch and they took a perfect polish - so I know it's the stones. So if they are jasper, they are a somewhat softer one.

Cayucos Jasper

Brecciated Jasper

I'm still poring over the 100 lbs of stones I brought back from California last week (the back of my car riding very low). I had a chance to cut open some of the larger pieces, many of which are of a  brecciated jasper that is common in this part of the Coast range (and several other parts of California).  This one is about 8" inches across and shows a fractured yellow-red jasper with a milky quartz filling.

Not a great picture, I admit, but you get the idea. Not sure how the quartz will polish, but we'll give it a try.  The diversity of the rocks along this coast is truly remarkable.  I suggest walking up Toro Creek near Cayucos, or for the best material, head straight to San Simeon Beach. Wow.

Beach Surprise : "Plume Agate?"

Beach agate, West Seattle

It's been a while since I was out on the beaches near home - blame it on cold weather and too many buckets already full of rocks, waiting for the polisher.

But on a handsome sunny winter day, I hit the beaches near Alki Point. I am always attracted by color and design, but especially if there is any sense of transparency, e.g. that glass-like quality that suggests "agate."

Here's one I found yesterday, an already well-rounded, naturally polished agate. My first thought was that it was what is known as a plume agate, in which impurities grow into the quartz often in lovely, lacy patterns. But when I took a close look at this, it does not have the typical "plume" patterns, but instead appears to be some sort of brecciated rock into which quartz has filled the gaps. Hard to tell what the green stuff is, but it's clearly fractured and shattered. Now, of course, it is suspended in the quartz matrix. Not sure what to call it, but it's handsome nonetheless.

Mystery Solved...

Brecciated Cherts, Channel Islands, CA

I collected these stones along the shore of Santa Cruz Island in California's Channel Islands last year. They were obviously silica-rich and took a nice polish, but were structurally all over the map: some were clearly banded like a conventional sedimentary rock, while others were fractured and chaotic.  I collected a dozen or so, but could not seem to find out what they were.

Then, recently, I struck up a conversation with a California geologist, who turns out to have done his PhD on the rocks of the Monterey Formation and immediately identified these as nice examples of brecciated cherts from the Monterey!   I still haven't figured out the exact mechanism of their formation, but they are pretty unusual in any case.

St. Kilda Oddity

 Granite/Dolerite Breccia, St. Kilda, Scotland

I collected this rock two years ago on the remote island of St. Kilda, off Western Scotland. It is about 9 inches long, about the size of an enormous russet potato.  I was stunned by the structure of the rock, composed of angular blocks of dolerite (Basalt) "floating" in a granite matrix. This was the largest one I could carry - but much of the island ( a World Heritage historical site) is made up of this stuff. No gem value, obviously, but just a wonderful piece of geology.