Archive for the ‘Quarries and mines’ Category

Pryal’s gold mine

3 January 2022

The Gold Rush was a bust everywhere in the Oakland Hills, with one exception. That was a short-lived mine, started in 1864, on A. D. Pryal’s ranch in the northern Rockridge neighborhood. This seems most unlikely at first blush, but the source is Titus Fay Cronise’s unimpeachable book The Natural Wealth of California (1868):

“In 1864, Mr. A. D. Pryal, owner of a large ranch about four miles east from Oakland, discovered a vein of auriferous quartz in the Contra Costa hills, which cross his lands. Some of the specimens from this vein were rich in free gold, and the mine opened under the name Temescal, paid well for a short time, but the dislocation of the strata, a little below the surface, rendered its further working unprofitable.”

The only remotely likely source for such an ore is a small body of highly altered mantle material, called silica-carbonate rock (also called listwanite or listvenite), that was caught up in the Hayward Fault. Long-time readers may recall a post of mine on the subject that involved this same locality. Here’s what the area looks like on the geologic map.

That’s College Avenue running up the left side and Route 24 in purple running along the bottom, with Chabot Road to its immediate north; Lake Temescal is in the corner and the silica-carbonate is the dark blue wedge just north of it between strands of the Hayward fault. When I explored it nine years ago, I bushwhacked up its western edge and found nothing. This weekend, I bushwhacked up its eastern edge.

This part of town has been heavily built upon since Pryal first dug it up, but old photos from (I think) the 1890s show the possibilities. The first shows the Lake Temescal dam and the creek below the spillway. What would’ve been the continuation of Chabot Road (then known as Pryal Lane) runs in front of the white house at the left. The little bridge at the bottom is where the next photo is.

Notice what a mess the hillside is above the dam. Anthony Chabot apparently sluiced it all into the reservoir when he built the dam in 1868. And notice what an erosional mess the streambed is. Nobody cared back then, or nobody downstream cared enough to sue Chabot.


Photos courtesy Bancroft Library via Online Archive of California

What caught my eye was the boulder at center left. Well, first, the streambank behind it looks like fault gouge, the pale powdery dirt that faults make by grinding rocks (and which I documented down at the London Road landslide). Anyway, the boulder at center left looks just like a big slickenside, the scraped-and-buffed surface that faults make by rubbing rocks.

The gist of all this is that a wide, complex fault zone like the geologic map shows could very easily carry slivers of rock from quite far away. And this is little known today, but in the early days there were curious, isolated reports of stones of gold-bearing quartz in our hills. At least two have popped up in my reading, one from north Berkeley and another from Leona Heights. So my hopes were not high as I set out on this traverse, but they weren’t zero either.

It was a real nice day. The streams had water and the ground was pretty firm and quiet. This is looking down at the head of Chabot Road, which was truncated by the freeway long ago. A strand of the fault is mapped there, but the road shows no sign of it.

I found bedrock this time. One bit was deeply weathered Leona volcanics, the same stuff that crops out uphill to the east (pink on the map).

This outcrop looked more like a strongly sheared and altered basalt, not unexpected in the Leona volcanics.

This outcrop, hard to tell; probably more of the same, brecciated.

None of what I saw appeared to be silica-carbonate rock or even leaning in that direction. But that’s what I would expect 160 years after a minor gold find petered out. I’m still not clear on what evidence led the mappers to think such a thing was here at all.

Besides, I was happy to find real bedrock at all during this visit, and there’s still a bit of the territory I haven’t set foot on yet — something for another day. After a long absence from the field, these rocks all looked beautiful to me anyway.

Blair Quarries (not the same as Blair’s Quarry)

6 December 2021

Walter Blair, the first resident of Piedmont, left his name in several places. The quarry he started in the 1850s, now near the foot of Blair Avenue, is now Dracena Park. Everyone called it Blair’s quarry. In the 1880s and 1890s, the amusement park he created in the canyon of upper Glen Echo Creek was a big deal. That was Blair Park.

This post is about the Blair Quarries, and this photo.


From Calif. State Mining Bureau Bull. 38 (1906), slightly massaged

The pit in this photo was the centerpiece of a rock-crushing district on Moraga Road, just above Mountain View Cemetery, that the state mining bureau described in 1906 as “Blair Quarries.” The main quarry was “near the summit of the hill, about 100 yards up the slope north of the road. It was opened in 1901.”

Just ten years before, that same land was part of Blair Park, “the most pleasant outing-place in the bay counties.” By all accounts (and they all seem to be collected at historyofpiedmont.com), the scenic canyon had been turned into a rustic garden fantasyland that included balloon rides, a bandstand, waterfall, garden maze, playgrounds and a “Venetian canal.”

After Blair’s death in 1888, the park eventually fell into the rapacious hands of the Realty Syndicate, which began to devour the valuable chert of the Franciscan melange zone starting in 1901. So Walter Blair had nothing to do with this quarry. At the time this photo was published, the Mining Bureau reported, “The company is opening a ‘blue rock’ quarry, of metamorphosed sandstone, on the south side of the road, and is tunneling in quest of rock for a quarry 50 yards west of and below the larger Blair quarry.” The Blair sandstone quarry, as far as I can tell, was where the Piedmont Reservoir sits today, at Scenic and Blair Avenues. If anyone can confirm that I would be most grateful.

When the city of Piedmont bought the property in 1913, the main quarry was finished. For a time, the Red Rock Quarry worked part of the site. Eventually the pit was filled in, and now the city’s corporation yard sits there. Today, the scene looks like this from the air:

and like this in the digital elevation map.

I think the photo shows the east face of the pit, about 60 feet high, late on a summer afternoon. Twenty men worked there, loading orecarts on at least four tracks. Fortunately, the cemetery hadn’t expanded as far as it has today, so it wasn’t disturbed by dynamite and dust the way St. Mary Cemetery was by the Bilger Quarry.

The odds are that much of the red chert you see in Piedmonters’ yards came from Blair Quarries.

Reichert’s pit, the Fruit Vale White Cement Gravel Quarry

13 September 2021

Starting on 8 June 1871, an ad in the Oakland Daily Transcript touted “White Quartz Gravel / for Sidewalks, Garden Walks, and Carriage Drives, It Makes A Beautiful And Solid Walk!” and offered this recommendation:

Mayor N. W. Spaulding, in his recent message to the City Council, said: ‘The only macadam walks which have so far proved successful have been made from [the Fowler quarry or] the white cement gravel found in the vicinity of Fruit Vale. The latter appears to be preferable because it becomes more solidified than any other material heretofore used, being less affected by the agencies of the weather. It has been used in some localities in this city for the last eighteen months. The peculiarities which recommend this cement gravel are: that when it is exposed to the elements it becomes adhesive and firm, is comparatively free from mud in Winter and dust in Summer. This makes it a complete and permanent improvement. Sidewalks made from this material are estimated to cost about 35 cents per lineal foot for walks eighteen feet wide.’ The subscriber has now got his road through to the White Cement Gravel Quarry, and will furnish at short notice any amount of Gravel for the above purposes, by leaving orders at Gardiner & Hunt’s office, Broadway, between Eighth and Ninth Sts., Oakland, and at the Brooklyn Postoffice.”

It was signed “L. Reichert, Fruit Vale.”

This material seems quite out of place for Oakland, and its properties appear unlikely too. But I’ve tracked it to land that Reichert owned above the Dimond district, at the end of today’s Maple Avenue, where a “gravel bank” is noted on the 1878 Thompson & West map.

And we’ve been here! It’s in the land south of the LDS Temple that was ruined by the London Road landslide in 1970. And that explains the peculiarities of the material. It was fault gouge: bedrock crunched into powder by the Hayward fault.

I believe its self-cementing character comes from a significant content of calcium carbonate, which is present both in the Franciscan melange on the downhill side and in the serpentinite a little ways uphill.

Despite the mayor’s endorsement, business for the Fruit Vale Quartz Company seemed to be spotty. Business broker Andrew Baird, of San Francisco, took over for a short time in 1873 under his own name; then Reichert sold the “inexhaustible” gravel pit, and the 25-acre parcel it sat on, in July 1873 to Elias L. Beard, a prominent wheeler-dealer based in Mission San Jose. Beard is shown as the owner in later maps (misspelled Baird, probably because the adjoining parcel was owned by Julia C. Baird). The 1874 city directory lists L. Reichert Jr. as a teamster with the Fruit Vale Quartz Company — perhaps the founder’s son.

Baird tried again to sell the parcel in 1875, 1876 and 1878, the year that Beard went bankrupt and lost almost everything.

I have little idea what happened after that, except that the State Bureau of Mines annual report 38, published in 1906, recorded this as the “Packard Quarry,” of which the newspapers make no mention. And as of 1912, the land was in the hands of the Realty Syndicate, part of its enormous hillside empire. A decade later the land began to undergo the process of residential subdivision that endures to this day.

Oakland, the city that borax built

24 May 2021

I was taking a bus ride and pondering what to write about for this post, when I looked toward Lake Merritt and found my topic written on the curb: “borax”.

This absurd-looking tag was surely a deeply historical reference to one of Oakland’s most memorable characters, Francis Marion Smith, who became the 19th-century version of a billionaire by exploiting the colossal borax deposits of the Nevada-California desert — and marketing based on the 20-mule teams that once hauled the ore to remote railheads. At least I hope it was, and not a new Oakland gang marking territory.

California is nicknamed the Golden State for the rare mineral that caused the Gold Rush — and the wildflowers too, of course — but Oakland sidestepped the Gold Rush and made its first wealth from the farms, orchards and oyster beds that fed San Francisco. (Its main geology-based industry was crushed rock.) A generation later, Smith became Oakland’s most influential citizen thanks to this boron-bearing mineral from the Nevada desert.

Boron is a cosmically rare element because stars can’t manufacture it, only high-energy cosmic rays that happen to strike oxygen or carbon nuclei in interstellar space. We are lucky that boron is rejected by minerals in the mantle and core and finds a home in the deep crust, mostly in the mineral tourmaline.


Schorl, or black tourmaline, is a boron silicate with a flexible formula that accommodates a wide mix of cations. Clear varieties are prized as gemstones.

In western North America, we’re luckier that crumbling continents and the volcanic activity that follows allow boron to rise to the surface, where it finds even more compatible mates and forms water-loving borate minerals in places like the dry lake beds of the Great Basin. The rise and fall of crustal blocks has decanted and concentrated all sorts of interesting minerals, from common salt and gypsum to lithium compounds and borates.

In the 1870s, borax (Na2B4O5(OH)4·8H2O) was an expensive compound well known to chemists, apothecaries and other specialists, but not at all a consumer good. Then Smith, a Wisconsin native drawn to the wild West, discovered a large deposit of ulexite (NaCaB5O6(OH)6∙5H2O) at Teel’s Marsh, in Nevada east of Mono Lake.


Fibrous ulexite or “TV rock” is available in any rock shop.

He’d seen enough mines by then to know what to do with it: refine it into borax, corner the traditional market for borax in chemistry and medicine, then sell the hell out of borax as the “foundation of a clean healthful home”: a disinfectant, insecticide, home remedy, and cleaning agent for fine clothing, now readily available to the person of ordinary means.

Smith succeeded in legendary fashion: his Nevada claim became the world’s largest borax mine, the first of many he operated, and a new industry was born from the abundance. That gave him the money to buy out his competitors as the opportunity arose and acquire their holdings in the desert. He grew rich; more than that, due to his marketing efforts — for instance, opening a borax shop in New York on Wall Street — he became known as “Borax Smith” at age 26 and, not long after, as “the Borax King.”

Smith moved from the Nevada desert to Oakland in 1881, where he proceeded to put his wealth to work, starting with a large estate and mansion in the Ivy Hill/Bella Vista neighborhood. As he gained experience building and running railroads to serve his desert mines, he consolidated the electric commuter rail lines of the East Bay under The Realty Syndicate, a land development partnership with Frank Havens. The Syndicate owned the majority of the high hills, developed many residential tracts around the Key lines, built the Claremont Resort and Key Route Inn, and planted the ill-fated eucalyptus plantations the length of the Oakland Hills, perhaps the city’s greatest ecocrime.

A hundred years ago, there was no more influential person in Oakland’s urban fabric than “Borax” Smith. The driven, meteoric entrepreneur was memorialized as the titular character Elam Harnish in Burning Daylight, Jack London’s most commercially successful novel: a man whose humanity blossomed not early with wealth, but later through love for a woman.

If only Oakland had borax deposits, or any boron-bearing minerals at all. But it doesn’t. I suppose if it had, Smith would have moved heaven and earth to turn that stuff into money. The only example I can show you is this tourmaline-studded ornamental rock from Pleasant Valley Court.

You might find some at a jeweler’s.