Archive for the ‘Quarries and mines’ Category

Boothite: Oakland’s own mineral

21 December 2020

This is the story of two Germans and their meeting long ago in Leona Heights.

Fritz Boehmer was a Prussian, born in 1831 in Magdeburg and trained in ironworking in his father’s foundry. In 1848, word arrived in Europe about fabulous deposits of gold in California, on the opposite side of the world. Europe was bursting in liberal-led revolution that year, shaking the continent’s political foundations from end to end and overseas. It was a restless time. When Fritz’s brother Eduard joined a group planning to sail to the gold country, Fritz begged leave of their newly widowed mother to see his brother off in Bremerhaven — and then climbed aboard himself, landing at San Francisco six months later as the world rushed in. In 1851, a shrewd and lucky man just twenty years old with a small fortune in gold, Boehmer bought a 160-acre plot in what is now downtown Oakland and embarked on a busy life that did not end until his death in 1910 and burial in Mountain View Cemetery. He was known for his generosity, good humor and love of song.

Boehmer was a founding father of the city of Alameda and had his home and main business there, a grocery, but he took a keen interest in his 92-acre holding in the hills east of Oakland along the old road to the redwoods, in the headwaters of Lion Creek behind the scenic grassy valley long known as Laundry Farm. He liked to call his place Friedrichsruhe, after Count von Bismarck’s country lodge near Hamburg, and his parties there were reported in the newspapers. (The papers and Boehmer’s 1904 reminiscence are where I learned most of the information in this post.)

Boehmer cast a shrewd eye over his land on Redwood Road, particularly its springs. He seized upon a story about Lion Creek told by an old Indian, who recalled that Lion Creek had roared with water after the major Santa Cruz Mountains earthquake of 1838. Although this phenomenon is now widely known among earthquake geologists (and my regular readers), Boehmer took it to mean that his land held a large underground river, and if he could tap that reservoir he could enter the water business.

In the 1890s his attention turned to the large natural deposit of ocher on his land, formerly a major resource for the Ohlone tribes and their trading partners. Soon he erected a mill at the site and launched a factory in Alameda that turned the ocher into “a good article of domestic paint.” The mill burned down a few years later, but by that time the deposit was nearly played out. Besides, he was busy subdividing his land and managing a hotel by Redwood Road, which he had paid to reroute at a lower grade. (If you can believe it, the old “blue road” was even steeper than today.)

Boehmer continued to keep his eye on the ground. In 1898 he was showing people chunks of rock from underneath the ocher, bearing veins of yellow metallic minerals, and spoke of mining gold and copper. That was the year when Laundry Farm was rebranded as Leona Heights by real-estate schemers with a plan to run an electric rail line there and sell lots to individual homebuilders.

By 1900 he had opened the Alma Mine, named for his daughter, and was selling trainloads of pyrite (the yellow mineral in question) to a chemical company that manufactured sulfuric acid from it. The professors of geology and mining and chemistry at UC Berkeley were visitors to his mine, and that’s how he met the second German.


View of Redwood Road from the west, 1949. The Alma Mine entrance was north of the road behind the trees. Oakland Library History Room image.

Waldemar Schaller was actually German-American, an Oakland native born to immigrant parents in 1882 and still living at home while he attended the Cal mining college. He undoubtedly spoke German at home. Later he described his early years: “As a boy I found my greatest pleasure in roaming over the hills around San Francisco Bay, collecting minerals and rocks, making many trips to Tiburon Peninsula hunting for lawsonite . . .” It was Andrew Lawson himself who nurtured his interest in geology, and Edward Booth of the chemistry department who introduced him to the Alma Mine.


Fritz Boehmer in 1901; Waldemar Schaller in 1939 (S. F. Chronicle/Mineralogical Society of America)

The brilliant young student of mineralogy got along well with the jovial old mine owner, who gave Schaller the run of his specimen collection. In 1903, still an undergraduate, Schaller published a 17-page paper in which he described the crystallography and chemistry of a dozen different copper and iron sulfide and sulfate minerals (plus red and yellow ocher) from the mine.

One of them, a delicate sky-blue hydrated copper sulfate, was new to science, and after providing a full description of its characteristics Schaller gave it the name boothite and established the Alma Mine as its type locality.

Later that year, Schaller won a position with the U.S. Geological Survey and remained there for the rest of his long and illustrious career. He described and named an impressive 41 minerals before his death in 1967. Boothite was his first — the kind of early triumph that can put someone on an epic path of achievement.

A few specimens from this historic locality are still extant. Maybe some have been handed down to living Oaklanders.

The changing identities of the Leona Quarry

9 November 2020

Last week I finally gave in and returned to the high hills — for exercise, as permitted by the county health authorities — and couldn’t resist a reconnaissance of the Leona Heights area. It’s Oakland’s boldest and most rugged region. Here it is from Knowland Park, above the zoo.

Most Oaklanders may know it, though, as the mountainside with the huge scar on it overlooking I-580, the former Leona Quarry.

The quarry was first opened by the Ransome-Crummey Company in 1904 and ended operations under Gallagher & Burk in 2003, but it changed hands (and names) several times over the years, making its detailed history hard to trace. Also, newspaper accounts often confuse it with the Leona Heights quarry, which was at the site Merritt College occupies today.

The quarry was first made feasible by an extension of the Laundry Farm railroad, above Mills College. It was originally high up a steep grade, as shown by the pick-and-hammer symbol in the 1915 topographic map.

I believe it was up there because the bedrock was well exposed, making excavation unnecessary at a time of heavy reliance on hand labor. The 1947 map shows that operations had moved downhill, and quite a bite had been taken out of the hillside.

And the 1980 update of the 1959 map shows the quarry scar at its ultimate size.

The whole time, this hillside was being quarried exclusively to make crushed rock. There was a huge demand for coarsely crushed stone in the days before asphalt and concrete pavement. The gold standard for city streets in the late 1800s and early 1900s was macadam, which has completely disappeared since then. You’ll only see it in silent movies.

A macadam road started with a shallow excavation that was filled with several layers of crushed rock, of successively finer grade, topped with fine gravel or rock dust. The jagged, blocky texture of crushed rock made macadam roads exceptionally firm in comparison to plain dirt or gravel, and they didn’t turn to mud in the rainy season.

As Oakland grew, filling in the harbor and airport and covering East Oakland with suburban tracts on an ambitious street grid, its quarry owners prospered, especially the well-connected ones who could arrange favorable contracts and keep wages low. Plain old crushed rock — road metal — was in high demand. Although there were still good markets for crushed rock after the macadam era ended, things were not the same. The Leona Quarry outlasted all of its competition in Oakland thanks to its remote location, good rail transport and ease of production. But eventually the city expanded to the quarry’s doorstep, the quarry ran out of easy rock and the show ended in 2003, when I took this shot of the north end of the property.

That’s when the site took on its next identity — a townhome district. The rock no longer matters.

But it used to. I think the Leona Quarry started running into problems as the standards in the rock business grew steadily stricter.

Leona Heights, the mountain, consists of a body of much-altered volcanic material of Jurassic age that I refer to on this blog as the Leona volcanics. Its eventful history left it impregnated with pyrite, iron sulfide, in many places. A little farther northwest, in the valley where route 13 splits from I-580, there was enough pyrite to support at least two mines. Down at the Leona Quarry there wasn’t as much, but it does exist and, as it does in the old mines, pyrite decays in the air and rain into iron oxides and sulfuric acid. The oxides turn brown, staining the Leona volcanics this typical color.

They also stain the stream water, as seen here in the headwaters of Chimes Creek above the quarry (and elsewhere in the hills).

The west side of the quarry was full of this “red rock” while the east side consisted of a dense blue-gray siliceous rock, more like this specimen I collected there back in 2009.

Whereas the red rock was useless for things like concrete aggregate because of its pyrite content, this was the good stuff. Nevertheless, the market for excellent road metal came to be dominated by huge outfits like Granite Rock — whose co-founder, Arthur Roberts Wilson, started his career at the Leona Heights Quarry back in the 1890s.

Meanwhile today, the former quarry is now a townhome plantation, set at the bottom of a high, steep rocky bowl.

There is no guarantee that the quarry’s second identity will last forever. Fire, earthquake and rockfalls can overcome any defense given enough time (although the Leona Quarry development has a GHAD that maintains the defenses). Zoning changes and real-estate fashions can undermine such enterprises as surely as physical hazards. There is no guarantee that anything we build will last a century, like the quarry did. Like the ancient philosopher said, everything flows.

Rocks of the Bilger Quarry

6 July 2020

It’s been twelve years since I wrote about the former quarry where the Rockridge Shopping Center sits today. Except for the pond, the whole space has gotten a makeover and it’s time for a fresh look. But first, some nostalgia. Back in 2008 the 24-hour “Big Long’s” was still there. I used to shop there; it had everything.

And flanking it was the big old Safeway with more businesses between and beyond, and the bank in the far corner. I used to bank there.

All of this is now gone, and the site is under intermittent redevelopment. Decades ago this was a giant rock pit, active for more than 70 years, that for a long time was the largest rock quarry in Alameda County. It was started by the Oakland Paving Company in 1870, and the name of Frank Bilger was associated with the succession of enterprises that produced crushed rock here, so it’s usually referred to as the Bilger Quarry. (Bilger learned the trade from his father, a German immigrant, and he surely pronounced his name the German way with a hard G.)

Now the Long’s site is a big Safeway, and the old Safeway and bank buildings are part of an empty lot. Only the water-filled pit on the east side is unchanged, and the walls show no sign of decay, which is a very good thing because it’s right next to St. Mary Cemetery.

The whole quarry site occupies a small body of quartz diorite, an intrusive (meaning it didn’t erupt) igneous rock that’s unusual but not unheard-of for the Franciscan Complex. It’s mapped as the purplish blob in the center labeled “Kfgm.”

It happens to be excellent rock for industrial and engineering purposes. The Tribune in 1890 wrote, “The material used by the Oakland Paving Company is a crushed blue rock, a trap dyke that is practically indestructible, submitting without injury to the hardest usage for eight or ten years without repairs, and with proper care, such as any pavement requires, lasting three or four times longer.”

The east end of the quarry exposes the bluish stuff. This exposure, right behind the Safeway, also has flaky veins of calcite. It’s very tough — not that I’ve used a hammer on it lately, but after seeing lots of rock you get a feel for this.

The west side consists of a much lighter material, a bit coarser grained and slightly less durable.

Between them is a contact zone that I recall as being black and sheared, with mineralization that was probably iron-manganese oxides. It was covered up when the new Safeway went in and parts of the rock face were fixed up for safety. I took this photo in 2018 from the roof parking lot.

There’s chainlink netting on the rock face, just in case it decides to start crumbling onto the roadway.

You’re always cautious about building inside an abandoned quarry, because rocks don’t last forever — that’s why they’re mostly underground, covered with soil. The experts have assured us it’s OK, and I trust them pretty well. The cemetery will last a good long while, and the former California College of the Arts campus, while it looks precarious perched above the other side, has passed muster too and someday will be apartments with good views.

What continues to impress me, every time I visit, is how different Oakland used to be. Throughout the late 1800s, the cemetery on one side and the CCA site (then it was the Treadwell estate) on the other were cheek-by-jowl with this huge operation that blasted three times a day, starting at six in the morning, and employed hundreds of men in producing crushed rock. But back then, rocks were money.

In search of lime

25 May 2020

I like to brag that Oakland contains more rock types within its boundaries than any other city in America. But alas, it’s missing one of America’s most widespread rock types: limestone. Yes, there are pods of dolomite limestone in the Claremont Shale, but that’s a far cry from what Oakland’s first outside settlers hankered for, which was real calcite limestone.

Limestone is essential for civilization because it’s the default industrial source of lime (calcium oxide or hydroxide), without which you can’t manufacture any kind of decent mortar, or plaster, or cement. Lime has been made for thousands of years by simply roasting limestone, which consists of the mineral calcite (calcium carbonate). This was traditionally done in a lime kiln, a stone furnace that was loaded with rock and firewood.

The Bay area does have bodies of limestone, and these were staked out early. But the nearby firewood supplies (i.e. forests) were soon depleted, and the industry was fitful and limited until reliable supplies of coal and, still later, oil became available.

One alternative to limestone in Oakland was oyster shells, which we once had in abundance. Unfortunately, many of the old Native shellmounds had oyster shells in abundance too, and this led to the end of them.

A few years ago I had the chance to visit the remains of an old-fashioned lime kiln in the Santa Cruz Mountains.

Another old site was on the coast near Rockaway Beach, south of Pacifica. I wrote a piece about it for KQED a while back that explains where most of our local limestone comes from, tectonically speaking.

This kind of industry lasted only a few decades. Around the turn of the last century, big manufacturers started to mine massive bodies of limestone. One was on the Santa Cruz County coast at Davenport; it supported a company town out there for a whole century. Another was in the South Bay near Cupertino, based in a quarry on Permanente Creek. One of Henry J. Kaiser’s early companies operated it, and when Kaiser eventually became head of an industrial giant, during World War II he took the name Permanente for the name of his innovative company health-care plan. The quarry is still digging, almost 80 years later.


By Steve Jurvetson from Menlo Park, USA – Flickr.com – image description page, CC BY 2.0, from Wikipedia commons

Another big limestone quarry was in American Canyon, in Napa County. But the one that fascinates me most is the former Cowell lime quarry, which sits between Walnut Creek and Concord, on Lime Ridge. For about 40 years, starting in 1908, this quarry exploited a thick deposit of travertine — hot-spring limestone. It supported a company town too. Now some of the workings are in Lime Ridge Open Space, where you can scrutinize these unusual deposits. They aren’t like anything else around.

This post was inspired by my maniac brother Steve, who explores the woods around his Lyme, New Hampshire home to locate old cellar holes. Now he’s branched into old lime kilns.

In other news, I’m happy to report that the latest Covid-19 guidelines now allow the use of public transit for outdoor recreation. This means that all of my geology walks and rambles can be undertaken again, and I’m looking forward to getting out there, taking due care of course.