Saturday, July 3, 2010

Serpentine: A Group of Minerals

Last updated 28Apr2013 at 6:35 a.m. PDT

As a property owner in California, and as a geologist, I'm annoyed about the recent BS (SB 624) the state legislature is up to in trying to delete serpentine as the state rock. First of all, as many have pointed out, serpentine is not a rock, it's a mineral group: the Serpentine Group, AKA the Kaolinite-Serpentine Group according to (shall we outlaw clay, also?). It is serpentinite (sometimes called serpentine or serpentine rock) that is a rock, the state rock of California – see Serpentine and Serpentinite from the USGS Cascades Volcano Observatory.

Serpentinite, the rock, is commonly formed of antigorite, lizardite, and chrysotile – all of which are Serpentine Group minerals – and other non-serpentine-group minerals such as talc, chlorite, magnetite, magnesite, brucite, chromite, sometimes relict olivine or pyroxene, and sometimes quartz and calcite (usually as later veins). Other mineral associations (for example at New Idria) include montmorillonite, coalingite, hydromagnesite, nepouite, pecoraite, and trace amounts of tremolite. Besides being host to a unique flora that can survive the plant-harsh conditions of high Mg, Fe, Co, Cr, and Ni (along with relatively low amounts of plant nutrients like calcium and potassium), serpentinite bodies in California have been host to most of the state's mineral deposits of chromite, magnesite, and cinnabar, and possibly some of the state's nickel occurrences. Other trace element associations can include minor copper and platinum. Chromium is of the non-hexavalent type (USGS Open-file Report 95-831, Chapter 5).

Asbestos is not a single mineral, and in fact isn't the name of any defined mineral at all. Asbestiform is a particular mineralogical habit that some minerals take: long fibers often in veins or masses. Asbestiform and fibrous, as crystal forms, are similar, with asbestiform being a more extreme version of fibrous. More minerals have a fibrous habit (for example, siderite, malachite, gypsum, celestite, chalcedony) than have an asbestiform habit.

The word "asbestos" comes from the Latin and Greek asbestos, meaning "unquenchable" or "inextinguishable" – also see more about the etymology of asbestos at the Online Etymology Dictionary, at Asbestos: Changing the Name of a Quebec Town, and at Merriam-Webster Online. According to my mineralogy book – the Manual of Mineralogy (after James D. Dana), 21st Edition by Cornelis Klein and Cornelius S. Hurlbut, Jr., 1993 – asbestos minerals in natural form have a length to width ratio greater than 100:1. Also, the book defines the term "asbestiform" as referring to "minerals that are mined for asbestos and possess fibrousity typical of asbestos—that is with small fiber thickness, flexibility, and separability." Not just any old mineral can be called asbestos or be described as asbestiform.

This is what the EPA has to say about asbestos:
Asbestos is the name given to a number of naturally occurring fibrous minerals with high tensile strength, the ability to be woven, and resistance to heat and most chemicals. Because of these properties, asbestos fibers have been used in a wide range of manufactured goods, including roofing shingles, ceiling and floor tiles, paper and cement products, textiles, coatings, and friction products such as automobile clutch, brake and transmission parts. The Toxic Substances Control Act defines asbestos as the asbestiform varieties of: chrysotile (serpentine); crocidolite (riebeckite); amosite (cummingtonite/grunerite); anthophyllite; tremolite; and actinolite.
Five of the minerals listed above that have asbestiform versions are amphiboles: riebeckite, cummingtonite/grunerite, anthophyllite, tremolite, and actinolite. The sixth mineral, chrysotile, is one of the Serpentine Group minerals. The asbestiform version of riebeckite is crocidolite, that of cummingtonite/grunerite is amosite. Anthophyllite is often but not always fibrous, and it is not always asbestiform. The EPA, nevertheless lists the mineral as "asbestos." The same is true for the minerals tremolite and actinolite (two end members of the tremolite-actinolite solid solution series, and to complicate things more mineralogically, both minerals form solid solution series with ferro-actinolite: tremolite–ferro-actinolite and actinolite–ferro-actinolite). Both tremolite and actinolite are commonly found in non-asbestiform habits, and consequently the asbestiform versions are sometimes referred to as "tremolite asbestos" and "actinolite asbestos," which seems to imply, incorrectly, that both minerals are entirely asbestiform.

Are we now going to take all samples of serpentine group minerals and any asbestiform minerals out of circulation, out of all teaching and personal rock and mineral collections? What?? Why? As Lab Lemming says (after pointing out that serpentine can be used for CO2 sequestration and that it prevents earthquakes by allowing faults to creep):
There are 20 forms of serpentine, only one of which is an asbestos mineral. The very dangerous amphibole asbestos minerals specifically mentioned in the bill are completely unrelated to serpentine.
The uproar about serpentinite, the rock, needs to die down: the legislature needs to back off. Otherwise one might think that the legislature was getting ready to fund the state of California (and themselves?) through litigation, rather than by any legitimate means.

GeoBlogosphere - Blogosphere Reports and Photos:
Photo of serpentinite ( Geology - Metamorphic Rock Types gallery)

Monday Mineral: Serpentine (Outside the Interzone, January 19, 2009)

The Other California: Geology and our State Symbols (Geotripper, December 2, 2009)

Rock 365 : Day 74 : Serpentine #365photos (hypocentre's posterous, March 16, 2010)

The Other California: A Journey to the Center of the Earth (kind of...) (Geotripper, March 31)

Dire Threat to Benign State Rock (Updated) ( Geology, June 19)

Unreasoned Fear of Serpents? We Geologists Need to Be Heard (Geotripper, June 24)

Losing Serpentine as the State Symbol of California? Why not educate instead? (Teaching the Earth Sciences, June 24)

CA SB 624 - Senator Gloria Romero's Bill based on BAD SCIENCE (Justin Zzyzx at, unknown date)

Serpentinite Under Attack, Part 2 ( Geology, June 30)

Libby and the Serpentine Killers ( Geology, July 2)

Hiking up Big Rock Ridge (Literrata, July 2)

Something Doesn't Feel Right About This: The Serpentine Issue in California (Geotripper, July 2)

In defense of serpentine (Lounge of the Lab Lemming, July 3)

More on the asbestos dust-up (Lounge of the Lab Lemming, July 4)

Throwing the Baby Out with the Bathwater: The Serpentine Issue in California (Geotripper, July 5)

Serpentine – SB 624, Senator Gloria Romero and ADAO (, July 5)

Politics, California and serpentine (Eruptions, July 6)

Save Our State Rock...Serpentine Gets A Bad Rep! (AFMS- American Federation of Mineralogical Societies blog, July 6)

Down with serpentine; or, clueless in California (The Volcanism Blog, July 6)

Fear and Ignorance winning out over Education and Knowledge: Serpentine Bill Sailing on through Legislature (Geotripper, July 7)

First Of All, California, It’s Your State Rock And It’s Called Serpentinite (Maitri's VatulBlog, July 7)

California Senate to drop Serpentine as state rock because of asbestos ties (Halfway to Concord, July 8)

Throwing the Baby Out with the Bathwater: The Serpentine Issue in California (Geotripper at Daily Kos, July 9)

A Letter to Governor Schwarzenegger and the California Legislature...About Serpentine!?! (Geotripper, July 9)

Wow...If I had a press secretary, would my assemblyperson call me? Update on the serpentinite issue in California (Geotripper, July 11)

Speak up for serpentine (Oakland Geology, July 11)

California's Unique Serpentinite Landscapes 1 (Geotripper, July 11)

California's Unique Serpentinite Landscapes 2 - And How Education is a Better Choice than a Press Secretary (Geotripper, July 12)

The Law Against Serpentine: The Attorneys' Arena (Andrew Alden, Geology, July 12)

In praise of green rocks (Active Margin, July 12)

California's Unique Serpentinite Landscapes 3 - Finding Beauty (Geotripper, July 13)

Save our serpentine! (California Dreaming - and the Reality, July 13)

California's Unique Serpentinite Landscapes 4: What can our state rock tell us about geologic processes on Mars? (Geotripper, July 14)

Geology Fail: California Moves to Disown State Rock (Discover Magazine, Discoblog, July 14)

An Introduction to Asbestos, clicks through to the next article (Andrew Alden, Geology, July 14)

Asbestos in a Nutshell: This miracle material has taught us some lessons (Andrew Alden, Geology, July 14)

Standing up for serpentinite (Highly Allochthonous, July 15)

A Serpentine-Inspired Rant (Haronic Tremors, July 15)

Serpentine Collecting Spots around California (map by Justin Zzyzx, July 15)

Unscientific California: How Scientific Illiteracy Threatens Serpentine and Biodiversity (Discover Magazine, The Intersection, Sheril Kirshenbaum, July 15, 2010)

California's Unique Serpentinite Landscapes 5: Doing What I Like to Do, and An Invitation! (Geotripper, July 16)

Calling on Californians: West Coast Represent! (Discover Magazine, The Intersection, Sheril Kirshenbaum, July 18, 2010)

California's Unique Serpentinite Landscapes: Eldridge Moores and California's State Rock (Geotripper, July 18)

What California most needs right now -- a defrocking campaign! (Classical Values, July 23)

Serpentinite Adored (Andrew Alden, Geology, July 23)
SB 624 Senator Romero’s Lies (and more lying liars that tell them) (, July 24)

Fighting For California's State Rock: What's Wrong With Senate Bill 624? (Geotripper, July 25)

Fighting For California's State Rock: What's Right With Serpentine? (Geotripper, July 25)

At home with serpentine (Oakland Geology, July 27)

My Serpentine Letter (Oakland Geology, July 28)

Rock in the limelight: serpentinite (Angelina Souren's Earth Blog, July 29)

My letter opposing SB 624: Serpentin(it)e (Perrykid's Posts, July 29)

An Update on the State Rock Debate in California (Geotripper, August 1)

San Francisco suiseki (Oakland Geology, August 1)

Serpentinite - California's State Rock (Gigapan by Ron Schott, August 1)

The Power of Words: The Debate over Serpentine in California (Geotripper, August 2)

Snaky Words like Serpentinite and Ophiocalcite (Olelog, August 3)

A #CAserpentine photo (Ron Schott, taken May 24, uploaded August 3; click #CAserpentine tag for more photos)

Learn the Facts About Serpentinite Before It’s Removed as California’s State Rock (KQED's Quest Science Blog, Brian Romans, August 5)

Serpentine, Science, and the politics of fear (Talkin' Rocks, August 8)

Save California's State Rock: CGF opposes SB 624 (CGF, Committee for Green Foothills, Greenfeet, August 9)

Standing on a Rock: Why the California Legislature Needs to Hear From Educators, Students and Scientists (Geotripper, August 10)

California Serpentine: To Assembly Member Lieu - A Question of Openness and Fairness (Geotripper, August 12)

Home Sweet Serpentine (KQED's Quest Science Blog, Jennifer Skene, August 16)

The California Serpentine Fight Goes On (Andrew Alden, Geology, August 19)

Politics of a rock (California's Islands, August 23)

Ding, Dong, SB624 Is Dead (Andrew Alden, Geology, September 2, 2010)

Erionite and Cancer in Cappadocia, Turkey (Olelog, November 5, 2010)

Serpentinite and mélange (Mountain Beltway, December 25, 2010)

Guest Post - Naturally Harmful Metals and Minerals (The Geology P.A.G.E., December 29, 2010)

Concerns over erionite dust as cancer source (Arizona Geology, January 5, 2011)

Mineralogical Society of America proposes a position statement on Asbestos (Lounge of the Lab Lemming, March 1, 2011)

Asbestos (Hudson Valley Geologist, March 9, 2011)

Maligned Minerals and Serpentinite in Sun (En Tequila Es Verdad, July 31, 2011)

My state’s official rock is a mineral! (En Tequila Es Verdad, Karen Locke, January 11, 2013)

Chrysotile (Sandatlas, March 3, 2013)

More about Serpentine, Serpentinite, and Related Topics:
A Serpentine Haiku: Peter B. Moyle, unknown date.

California State Rock: Serpentine: State Symbols USA.

Klamath-Siskiyou Wilderness Wild and Rugged Sanctuary: California Academy of Sciences – about flora and fauna and serpentinite (among other things).

California Floristic Project: Centres of Plant Diversity, Smithsonian Institution.

North American Serpentine Flora, U.S.A. and Canada: Centres of Plant Diversity, Smithsonian Institution.

Day, D., 2005, Rugged Plants Struggle to Survive on Barren Serpentine Soil: Northern California Geological Society Newsletter, February 2005 [also reprinted here].

Hotz, P. E., 1964, Nickeliferous laterites in southwestern Oregon and northwestern California: Economic Geology, v. 59, no. 3, p. 355-396 [abstract].

Rinaudo, Caterina, Gastaldi, Daniela, and Belluso, Elena, 2003, Characterization of chrysotile, antigorite, and lizardite by FT-Raman spectroscopy: The Canadian Mineralogist, vol. 41, p. 883-890.

Wrucke, C. T., 1995, Serpentine- and carbonate-hosted asbestos deposits, in USGS Open-file Report 95-831.

And Some Other News-Type Items:
Recreation Wrongly Targeted in Clear Creek Closure (Blueribbon Coalition, May 1, 2008)

Several Sierra trails are toxic, group says (San Francisco Chronicle, SFGate, June 23, 2010)

California's state rock raked over the coals (San Francisco Chronicle, SFGate, June 24, 2010)

Why rock this boat? Decertifying the California state rock, serpentine, because it contains asbestos won't alleviate the cancer that the substance causes. (Los Angeles Times, July 28, 2010)

Should California's state rock be stripped of its title because it contains asbestos? (Los Angeles Times, July 2, 2010)

Lawmakers have serpentine rocks in their heads (San Francisco Chronicle, SFGate, July 3, 2010)

Letters to the Editor (San Francisco Chronicle, SFGate, July 3, 2010)

California Looks to Shun State Rock Over Asbestos Content (DailyTech, July 6, 2010)

Is Mother Nature Really Out To Get Us? (Carnegie Forever, July 6, 2010)

Serpentine Politics (Burrito Justice, July 6, 2010)

Dan Walters: California state-rock bill has serpentine agenda (Fresno Bee, July 9, 2010)

What's Underneath the State Rock Bill? More Lawsuit Abuse! (California Civil Justice Blog, July 9, 2010)

Throwing the Baby Out with the Bathwater: The Serpentine Issue in California (Geotripper at Daily Kos, July 9)

Rock stuck in a hard place (San Francisco Examiner, July 10, 2010)

Personal Injury Lawyers Between a Rock and a Hard Place - Lawsuit Industry Picks a Fight With Geologists and Friends (California Justice Association of California - CJAC, July 12, 2010)

State rock debate rocks Twitter The Sacramento Bee, CapitolAlert, July 13, 2010)

Lawmakers want to get state rock off the books (The Oakland Tribune,, Political Blotter, July 13, 2010)

Outcry as State Rock Toppled (The Bay Citizen, July 13, 2010)

California May Drop Rock, and Geologists Feel the Pain (New York Times, July 13, 2010)

California May Drop Its Official State Rock (New York Times, July 13, 2010)

The battle over the California state rock (CalCoastNews, July 14, 2010)

Geology Fail: California Moves to Disown State Rock (Discover Magazine, Discoblog, July 14, 2010)

Calif may dump 'state rock' that contains asbestos (AP, Yahoo! News, July 15, 2010)

Unscientific California: How Scientific Illiteracy Threatens Serpentine and Biodiversity (Discover Magazine, The Intersection, Sheril Kirshenbaum, July 15, 2010)

Geologists take to Twitter to save beloved rock (Mother Nature Network, July 15, 2010)

Lawmakers Look To Change Cancer-Causing State Rock (The Huffington Post, July 15, 2010)

NYTimes, Calif. Press, twitterers too: Big ruckus over state rock serpentine, asbestos activists, and demonization of a stone (Knight Science Journalism Tracker, July 15, 2010)

Geologists protest bill to remove state rock (San Francisco Chronicle, SFGate, July 16, 2010)

Cut and thrust election online (The Sydney Morning Herald,, July 16, 2010)

Wait, they're going after the state rock? ( News Blog, July 16, 2010)

Political call to 'defrock the rock' (The New Zealand Herald,, July 17)

Lawmaker seeks to defrock 'toxic' official state rock (BBC News, July 17, 2010)

My Word: Rocky stance on serpentine status as state rock (Eureka Times-Standard, July 17, 2010)

My Word: Rocky stance on serpentine status as state rock (The Ukiah Daily Journal, July 17, 2010)

Our Opinion: Between a rock and a hard place (Imperial Valley Press,, July 18, 2010)

Calling on Californians: West Coast Represent! (Discover Magazine, The Intersection, Sheril Kirshenbaum, July 18, 2010)

A serpentine approach toward more asbestos litigation (, July 18, 2010)

Serpentine rocks on as CO2 vacuum (San Francisco Business Times, July 23, 2010)

Between a rock and a hard place: California’s rock debate (89.3 KPCC, Southern California Public Radio, podcast with Garry Hayes and Brian Wernicke, July 23, 2010)

'Serpentine, Shelly, Serpentine' (El Defensor Chieftan, July 24, 2010)

Geologists Revolt Over Proposal to Change California State Rock (Gawker, July 24, 2010)

Natural Wonders: California state rock in danger of demotion (Chico Enterprise-Record,, July 24, 2010)

Hamlin: Don't laugh -- this is really important legislative stuff (The Reporter (Vacaville), July 25, 2010)

Californians Debate Fate of Official State Rock (Voice of America,, July 26, 2010)

The irrational fear of our state rock (Los Angeles Times Opinion, July 27, 2010)

Caught between the state rock and a hard place (Stockton Record,, August 2, 2010)

Ashton: MJC teacher on a mission to vindicate state rock (The Modesto Bee, August 2, 2010)

Why California is between a rock and a hard place (Manteca Bulletin, August 5, 2010)

Serpentine to Avoid Flying Serpentine! (OCWeekly, August 5, 2010)

‘Save the rock’ or ‘Drop the rock’? (The Orange County Register, August 12, 2010)

Editorial: Stop ridiculous debate over state rock (The Oakland Tribune, InsideBayArea, August 13, 2010)

State rock controversy enters new phase (The Sacramento Bee, Dan Walters, August 18, 2010)

Signs: "Warning Unsafe To Enter" and "Everything Outside Might Be Dangerous"

I will be updating the Geoblogosphere and news links as more posts and articles are written.


Diane AZ said...

Good thing you're raising awareness about Serpentine. I lived in California for 35 years and didn't know it was considered the state rock even though it's a group of minerals. Interesting!

Silver Fox said...

Well, serpentinite (or serpentine rock) is a fine state rock for California - it's an unusual rock, found more in California than any other state, and it's found there because of CA's plate tectonic setting explained well by Garry Hayes.

Silver Fox said...

Serpentinite is not unique to California; in the U.S. it is also found in Oregon and Washington (and Alaska? I've never seen any there), and it's found in other places around the world, most notably in other subduction and collision zones (as pointed out by CJR in a comment at Geotripper).

Serpentinite is well-exposed and at least sometimes easy to get to in California, like at New Idria. In Oregon, one has to do some bush beating to see much serpentinite. I've not seen the serp in Washington, so can't comment on it's visibility or ease of access.

Dan McShane said...

I always thought California's recognition of serpentine showed sophistication.
Lots of serpentine in the Northwest Cascades and san Juan Islands. These rocks were likley accreted to the northern California/southern Oregon margin and translated northward during the late Cretaceous. Exposures near along the shore of Washington Park in Anacortes and chunks can be seen in the debris on the Swift Creek alluvial fan east of Nooksack, WA.

Silver Fox said...

Dan, thanks for pointing out serpentinite localites in Washington, and the way it got there. As for CA, they just seem to be losing it.

Silver Fox said...

For some reason, Blogger is not showing any further comments of mine on this post, and I see others around are having some problems. I am getting email notifications that I've added a comment!

If you think you're having a problem getting comments through, send me an email.

Thanks, sfx.

Silver Fox said...

Comments appear to be fixed.

Maitri said...

Galena is the state mineral of Wisconsin. Do you see us dying of lead poisoning from our samples? Are we going out there to inhale and lick these rocks (ok don't answer that last rhetorical question)?

And what is wrong with California that when employees are furloughed and the state is BROKE ASS, this is what they find the time to legislate about?

Silver Fox said...

Maitri, it's all kinda crazy, I agree! Banning the state mineral of Wisconsin would be equally dumb. (I won't mention rock licking, oops.)

Read the latest post at Geotripper, if you haven't already, about banning other things like poppies and quartz and gold and...

Dan McShane said...

Serpentine is a great state rock. I always thought it gave California an air of sophistication regarding geology as one would assume they would be obsessed with gold being the golden state and the gold mining history.
Washington State has lots of serpentine in the north portion of the state at a variety of terrain boundaries. The easiest to see is on the north shore of Fidalgo Island in Anacortes' Washington Park.

Silver Fox said...

Dan, you must have had the same problem I did in seeing my own comments - I saw your first one, and it never seemed to disappear for me, but my comments never even posted as far as I could tell.

Unknown said...

I too am shocked at this attempt to de-throne serpentine as CA's 'state rock.' My colleagues and I have dedicated our lives to study these rocks and the rich biological diversity found in habitats overlying these rocks. Most SERPENTINITE contains little to no asbestiform chrysotile and does not pose any significant health risk in its natural state. The fact that chrysotile presents adverse health effects as a reason for removing SERPENTINITE as state rock is as flawed as saying that the Ridge-nosed rattlesnake should be removed as the state reptile of AZ as it is poisonous to humans. The grizzly bear is hazardous to humans too so why is it the state animal? Because we killed it off? UV is clearly more harmful than exposure to SERPENTINITE which contains minimal amounts of chrysotile asbestos, not the tremolite asbestos, which is known to be harmful to health. Health risks, if any, depend on the asbestos type (chrysotile versus tremolite), exposure frequency, and exposure level. All three factors are very low in most SERPENTINITE landscapes around the world, particularly in CA. There are essentially no documented cases of anybody having developed mesothelioma from the casual chrysotile exposure received from naturally-occurring chrysotile found in SERPENTINITE in CA. I urge that SERPENTINITE remain in place as the State Rock. It is part of our natural heritage, one that has served CA well. Clearly, there is more to worry about these days than waste time de-throning a rock!

Silver Fox said...

You make some very valid points, Nishanta. Not sure if we're being heard, but trying!

Garry Hayes said...

This is a great resource, Silver, thanks for pulling it together!

Silver Fox said...

Thanks, Garry! I just keep on adding, and adding, and adding...

TTRENT said...

I am a biologist and a research biochemist specializing in natural occurring (NOA) "asbestos" in California. The legislature is a day late (meaning decades late) and a dollar short (meaning, well more) and working on the complete wrong subject. ADAO is not intentionally misleading, but they as a group are misleading. Natural occurring forms of asbestos occur in all states in the ground from soft friable easily airborne to hard rock hard to blow up with dynamite. In California communities have lived on all forms of natural occurring Chrysotile "asbestos" for well over 200 years. Intensive studies of death certificates shows no excess lung cancer or any excess mesothelioma at Chrysotile sites at all. San Francisco is the most contaminated Chrysotile city on earth. Yet small communities in California who have lived on Tremolite asbestos deposits for only short periods, show large quantities of excess mesothelioma. Not just in humans but in animals too. Huge levels of death from a non serpentine NOA. This news regarding Tremolite was published in the newspapers, mostly front page news, in Sacramento for 8 years straight! What do the legislators do? Why they OK "asbestos" epidemics by refusing to address the problem, and they condemn the innocent serpentine rock without even realizing what they are doing. For those who don't know, this exact same subject has nearly killed entire communities in the United States. Groups such as ADAO focusing on Chrysotile "asbestos" to the exclusion of the far more dangerous forms of "asbestos" have lead to the communities of Libby Montana and Jefferson Parish Louisiana having enormous non serpentine epidemics of human death. The legislators could actually do something useful here, but not while they are mislead by non scientists such as ADAO.

Silver Fox said...

Thanks, T Trent, for adding your information about these studies. I wonder if you have any links or doi's?

Maureen Hurley said...

Thanks for the link to my blog post, "Hiking up Big Rock Ridge." It was written before I knew of the the SB624 hubbub.

And thank you for your detailed information of Serpentinite. My rock books are packed away and I knew most of what I was reading about SB624 was disinformation.

In the US, tobacco kills 390,000 to 448,000. 2ndhand smoke—50K. Alcohol—80K. Cocaine, heroin, aspirin & asbestos kill 2,000 ea. #CAserpentine 0.

Silver Fox said...

Maureen, I enjoyed your post, have been on the road not able to read online or comment much.

ttrent said...

Hi Silver Fox,
Send me an e-mail I will insure that you recieve a comprehensive list fo studies. Then you may post them as you see fit.
Best regards,

Silver Fox said...

Just responded, sorry for the wait!