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Asbestos in California's State Rock? Not Really

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California lawmakers are expected to vote this week on SB 624, which could demote serpentine from its lofty place as California's state rock. This is a spectacularly silly decision based on shoddy scientific evidence, and here's why. According to biologist David Lowry:

In a misguided attempt to “educate” Californians about the dangers of asbestos, State Senator Gloria Romero introduced a bill (SB624) to remove serpentine as the state rock. The result has been a widespread revolt among geologists-at least in the twitterverse under the hashtag: #CASerpentine. ...Serpentine is commonly found in the hilly areas of California. It usually has a lovely smooth green or whitish tinge and its chemical composition has other characteristics fascinating to geologists, which I won’t detail here…except to include that some forms contain a small amount of asbestos, which leads us to our current predicament.

You all remember asbestos, right? That lung cancer-causing white powdery substance that closed down your school gym as a kid for a year when they discovered it in those flame-resistant tiles (which seemed like a good idea at the time) lining the ceiling. Yep, it’s nasty stuff. We know we don’t want it around and can move on, right?


The truth is that most serpentine does not contain asbestos. And even for the few samples that do, someone would have to expend considerable energy crushing the rock into something that could be inhaled to come even close to increasing his or her risk for cancer.

UC Davis geologist Eldridge M. Moores has compiled a list of scientific truths about serpentine:

  • Serpentine is closely associated with gold deposits in the foothills, with the California Gold Rush, and California’s history.
  • Serpentine is formed by hydration of rocks (peridotite) that come from the Earth’s mantle, the layer beneath the Earth’s crust.
  • Principally, serpentines and associated rocks are part of rock suites called ophiolites that are fragments of ocean crust and mantle emplaced in continents.
  • Ophiolites are widespread in California-in the Coast Ranges, the Klamath Mountains, the Sierra Nevada, along other parts of the western margin of North America, in the Appalachians, and in Latin America, Eurasia, and elsewhere. Thus these rocks are important for a full understanding of the complex evolution of the California landscape and our planet.
  • Serpentines are fairly easy to identify, being mostly shiny black or green. Many serpentines are also weak rocks and prone to landslide. Having serpentine as California’s State Rock calls attention to these issues in many places; and provides a “teaching moment.”
  • The asbestos in serpentine is mostly the less-harmful form, chrysotile, rather than the more dangerous form - amphibole. The latter forms by different geologic processes from a variety of rock-types.
  • Having children possess samples of serpentine should not endanger their health any more than samples of many other rocks.
  • Many rare species of plants grow only on serpentines, including special trees, shrubs, and non-woody plants. California is world-famous for these plants: indeed many grow only in California. These plants also provide a “teaching moment”.
  • Serpentines and their original mineral, olivine, are increasingly viewed as an ideal repository of carbon dioxide, because they chemically combine to fix the CO2 in the solid mineral magnesite (magnesium carbonate). This possibility is important for the future of California serpentines, for the US’s efforts to control its greenhouse emissions, and provides an additional “teaching moment” for all of us.
  • Serpentine plays an important role in small movements (creep) where serpentine is present along active faults, reducing the hazard of large earthquakes.
  • “Defrocking” serpentine as the California State Rock is not going to make any of these issues go away. It will, however, make it more difficult to communicate the many issues, both bad and good, to the public in California.

Judgment on the bill happens this week! And here at LAist, we think that when policy-makers make "scientific" decisions based on nonsense, it is our responsibility to speak out. So what can you do?
Get in touch with California politicians:

Support for LAist comes from

1. Senator Feinstein

2. Senator Boxer

3. The Governor

4. Gloria Romero, who is naively pushing for this

5. Your state assembly person.

Tell them you want Serpentine to remain the California state rock!

(h/t Sheril Kirshenbaum, of The Intersection blog)