My e book Deep Oakland relies on the massive number of rocks and geologic options we’ve on this city and close to it. In that method Oakland is like California, a state of incredible geological selection. Certainly, in Oakland yow will discover extra rock sorts than in some other metropolis in America.
That number of rocks is intriguing. Does Oakland, like California, have some cool minerals? Do we’ve any gem stones? The reply to each is “Sure, type of.”
Oakland has no minerals of treasured worth besides conceivably a sniff of gold.
The traditional Gold Rush skipped the East Bay; all anybody observed alongside the entrance of the “Contra Costa Vary” was a couple of heat springs and oil seeps and sulfide deposits. And but there’s the one report of the short-lived Temescal gold mine on A. D. Pryal’s ranch within the North Oakland hills circa 1864, a narrative not repeated in any of the native histories.
There have been uncommon studies of gold-bearing quartz elsewhere within the East Bay hills within the 1800s, none of them by respected geologists. One specimen, although, was supposedly discovered by a prospector within the Leona Heights space. The landowner he confirmed it to, Fritz Boehmer, was impressed to dig round his property there, the place he discovered three minerals price a rockhound’s consideration.
Boehmer already knew concerning the first mineral, one the Ohlones had mined and traded for a lot of centuries: ocher. Actually he had just lately completed mining it out to produce crimson pigment for a paint manufacturing unit. These things.
I take into account ocher to be essentially the most beneficial mineral in Oakland, given its lengthy historical past as a useful resource. It’s additionally essentially the most collectible, in case your gathering tastes run that method.
Digging round, Boehmer encountered a big physique of sulfide minerals beneath the ocher. He began a mine and named it for his daughter Alma. The Stauffer Chemical Firm constructed a plant on the Melrose prepare station to course of the ore from the Alma Mine in addition to its personal Leona Mine close by. Pyrite, processed to make sulfuric acid, was the pay dust. It occurred in thick, pure veins. These things.
For some time, then, this was essentially the most beneficial mineral in Oakland. It’s not collectible, although, as a result of all of the mine workings have been sealed for a few years.
Boehmer’s third mineral was a specimen crusted with sky-blue crystals that caught his eye quickly after the Alma Mine opened. He lent it to a pleasant mineralogy pupil at UC Berkeley, who decided the crystals represented a mineral new to science that he named boothite, a narrative I inform elsewhere. Boothite is uncommon and delicate; despite the fact that Oakland is its sort locality, it’s gone and also you’ll by no means discover it right here. Though maintain your eyes peeled at property gross sales and swap meets, as a result of there simply may be historic specimens from the Alma or Leona Mines in circulation.
For collectible Oakland minerals, that’s just about it.
For treasured stones in Oakland, aside from gold (see above), perhaps we’ve a pair, for those who rely semiprecious lapidary-type stones.
A few of our serpentine rock could be compact and arduous sufficient to qualify as “California jade,” one thing like this fist-sized merchandise from a Millsmont again yard.
It might make a good-looking pendant or tablet field.
Our cherts don’t have the requisite qualities. The youthful white chert of the Claremont Shale isn’t arduous sufficient, regardless of its visible curiosity. It’s categorised as porcelanite, remodeled solely partway towards the totally microcrystalline silica often known as agate.
The older crimson and multicolored chert of the Piedmont block’s Franciscan melange is difficult and lustrous — jasper, actually — however not sound sufficient to face as much as sawing and sharpening, though perhaps somebody on the market has tried.
The basalt rocks of Sibley Volcanic Regional Protect are mentioned to comprise nodules of correct agate. (Extra appropriately, the nodules are known as amygdules, and so they normally encompass different minerals.) Collectors widen their eyes on the point out of Sibley’s blue agates, however I’ve by no means seen one and the one image I do know of, on Steve Edwards’s fantastic californiageology.internet website, is extra attention-grabbing than spectacular. On condition that, plus the restrictions on gathering, I counsel respectfully that “Berkeley blue agates” be considered legendary.
Are we out of luck, then? Possibly not, if we glance past typical stones. I’m not a lapidarist, so perhaps my concepts are lame, however how about attempting our San Leandro gabbro?
If I had my very own rock noticed and lapwheel, although, I believe my first candidate can be the vague blue-green nodules discovered right here and there all through the Leona volcanics. The matrix is similar arduous, sea-changed volcanic ash discovered in all places else, with a splash of celadonite accounting for the colour.
Anybody need to strive these?
