Black Oak was the name of an old mercury mine high in the northeastern corner of Sonoma County. Why the mine was named for this tree is unknown, but Black oaks are found throughout the county, so it’s quite likely there was one growing nearby, perhaps supplying a welcome pool of shade on a hot day.
Right now, Black oaks are sprouting new leaves. If you take a close look, you’ll find the emerging foliage in striking shades of pink and red — colors you’d expect to see on a wildflower, rather than an oak tree.
As they mature, Black oaks’ leaves turn deep green and have points at the tips of their lobes (unlike Valley oaks and Blue oaks). Over the next few seasons, the leaves finally turn bright yellow before dropping in the fall. Black oaks can claim to be one of California’s “most colorful oak trees.”
The love of trees is a nearly universal human trait, perhaps an echo of the distant past when we climbed them for refuge from dangerous predators, but the beauty we find in certain species is also partly cultural. There’s a story about someone pointing out the impressive Valley oaks at Santa Rosa Junior College to Pomo elder Mabel McKay. They asked, “aren’t they beautiful?” She surprised her companion when she scoffed and called them “mush oaks.”
Acorns have been a staple of the Pomo's diet since time immemorial. And McKay knew the difference between different kinds of acorns through their taste and texture. Valley oaks are not on the list of favorites, but her people, like many Indigenous tribes, prefer Black oaks for acorn soup, acorn bread and other foods.
Black oaks’ acorns require less work than other oaks to make them palatable and they can be stored for several years. Mature Black oaks in full bearing were a significant source of food — a kind of wealth really, but it took time to get there. Black oaks take about 80 years, one human lifetime, to mature. As the tree got bigger, it was pruned into a broad crown with low branches. Once trees reached maturity, they provided a century or more of plentiful harvests.
Eventually, even old oaks go into decline. By the time the tree has toppled over, one of its offspring was ready to take its place.
The men who set their shovels and picks to the ground at Black Oak mine had dreams with a much shorter timeline. Between 1938 and 1940, when the mine opened, the price of mercury more than doubled. They workers were probably hoping to get rich quick, but if they did, it didn’t last long. When the price of mercury plunged in 1944, the Black Oak mine was abandoned. Only a slim legacy was left behind — just an enigmatic name on the map and, very likely, piles of hazardous tailings and tunnels for some future generation to deal with.