Why so many brown agates?

As a very happy resident of Southern California, land of abundant field collecting locations, I'm often suprised by how many locations I don't know about. I've often passed the former silver mine, turned to amusment park ghost town and thought about checking out the agate deposits I had heard about. Truth be told, agates just don't get my gears cranking. I'm a mineral fanatic. I had seen on some maps that there was an old Borate deposit and I pictured it as some crazy pits in the flats of the desert, complete with crusty degrading wood. Yet, I had no urge to go there, because I just didn't know where it was exactly.

This year Brandy and I took our niece to the fall Costa Mesa mineral show. While visiting with Steven Wolfe he invited us to go collecting out on a field trip with the Santa Ana rock club to Calico, the Minniola road agate/petrified palm root/jasper location. I had just been reading about some Celestite deposits in Southern California and I had noticed that there was a deposit of Celestite after Selenite at the Borate mines of Calico Mountains. Our niece seemed excited to go collect some rocks, so we drove up to Barstow on a wonderful mild fall day. When I got to the location we collected with Steven for awhile, taking an hour to go visit the "Calico early man dig" just a mile away. Steven told me there he remembered about the location and with the help of an old guide book, set off for a day in the Calico mountains.

After finding out along the way that Mule Canyon is a very popular area for camping and off road vehicle driving, we found the borate mines very easily, as the dumps were right along the main mountain desert road. Parking and hiking off into wash that replaced the 100 year old road we started finding lumps of Colemanite, Selenite veins, ugly typical brown California agate and other odd things. The occasional Ulexite cluster, resembling Howlite, but clearly consisting of tiny needles. Along the road up out of the wash and closer to the actual mines we found lots of broken clusters of Colemanite and tons of Selenite. Brandy was excited to collect Colemanite crystals, I was bummed that we didn't find any Celestite after Selenite, but we planned on going back. I was going to search those hills for the mythical Celestite after Selenite.

The next day, while cleaning some other rocks, I poked my hand into the box of rocks dumped out of the Calico trip and pulled out a dark looking agate...which turned out to be this...



WOW! We had found one while we were out! A nice big one too! I wonder if they are all like this, so we planned a trip back to the location right away. Without kid in tow, waking up nice and early, we set off to tackle this location again. However, I did want to take a little side trip to the hills above Mule Canyon, through Tin Can Alley. I heard there was good moss agate back there and while not a fan of agates, it would be good to know if there was "good stuff" back there, incase I lead a field trip to the area in the future. As soon as I parked the car I noticed these super cool orange bubbly chalcedony specimens on the ground. I found one very cool clear and orange Quartz crystal and I knew we were in the right spot. On the way out to the hills with the Moss Agate we found tons of these cool orange Chalcedony pieces, agates, Sagenite included agates and Brandy found these two winners...





Don't get me wrong, I found some nice pieces too, but Brandy rocked it out with these two great Chalcedony specimens!

Now, to attack the Borate mines with a bit more knowledge!

Found a nice piece of Celestite replaced Selenite right away and four more on the way up to the mine. While up in the hills, Brandy set about working the Colemanite boulders into smaller managable specimens while I set about exploring the hills, looking for Celestite float. I wondered all over the area, mapping out the area in my head, noting what was in each canyon. I didn't find a speck of Celestite.



But I did notice some Colemanite clusters that had these odd water clear crystals in the vugs, which I had thought was another generation of Colemanite at first. When I finally got back to Brandy she had been wrapping up all the clusters she had found and I showed her my specimen. She told me she got a whole bunch of them like that and I didn't pay much notice, because, hey...Colemanite! Who in the world wants Colemanite? Borates are the most under appreciated minerals in the world...next to amphiboles. It wasn't until we got home and started cleaning the specimens that we noticed...oh my...all those crystals are actually Celestite.



After cleaning the contents of two collecting trips we got about a flat of decent Colemanite crystals and a flat of nice Selenite crystals and Celestite on Colemanite geodes. The Selenite reacts strongly to UV light and over 9000 thousand million tons of Selenite veins must cross through those hills. Some of it is rather clear and well terminated, while most of it is thin veins of "satin spar" variety.



The Colemanite, while fragile and prone to crumble, shows some nice clear crystals in tons of different habits. What a weird mineral. The best crystals are the clear ones, but they are in a matrix of...more Colemanite...all breaking apart. So, here is a picture of the super stable type, the more creamy yellow colored Colemanite found on the dumps.



The piece has a weird look to it, similar to those crazy tourmalines coming out of Vietnam. Of course, Colemanite and Tourmaline are both Borate minerals! =)

After two trips to this region I have discovered that not only was this spot easy to get to, it is really fun, full of collecting spots and I haven't even scratched the surface! We can't wait to go back and explore more of this century old mining district...

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