Henry
spending too much on rocks
Member since January 2013
Posts: 452
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Post by Henry on Apr 12, 2018 23:25:04 GMT -5
Hello everyone. So I made an excursion to the jade area of Big Sur, California. I found some pieces that are undeniably nephrite jade. But then, I find this piece that makes me scratch my head. Here's some info: Location: Willow Creek, Big Sur region. California. Hardness: Leaves steel on all areas. Luster: Some gray areas dull, though most of it waxy. Weight:???Heavy and dense. Translucency: Highly translucent in the green areas. The non-waxy dull areas...no. At first glance I was thinking jasper/chert. But it didn't fit the pattern of "typical" willow jasper/chert. A Big Sur jade expert highly doubts that it is nephrite. So what is this matrix with unknown inclusions?
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Post by Pat on Apr 12, 2018 23:50:17 GMT -5
Looks serpentinish.
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lookatthat
Cave Dweller
Whatever there is to be found.
Member since May 2017
Posts: 1,360
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Post by lookatthat on Apr 27, 2018 18:53:20 GMT -5
serpentine is always my default answer.
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Post by sntacrzrocksfossils on Jun 18, 2020 13:10:58 GMT -5
I know this thread is from a couple years ago, but i have found similar stones at Willow creek big sur, and I have had a gentleman from New Zealand with similar geology in his home town tell me it could be hydrogrossular garnet.
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Post by sntacrzrocksfossils on Jun 18, 2020 13:18:40 GMT -5
I’d like to post a picture but I don’t know how to :/
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pizzano
Cave Dweller
Member since February 2018
Posts: 1,390
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Post by pizzano on Jun 18, 2020 13:43:45 GMT -5
I know this thread is from a couple years ago, but i have found similar stones at Willow creek big sur, and I have had a gentleman from New Zealand with similar geology in his home town tell me it could be hydrogrossular garnet. If that material is indeed Hydrogrossular Garnet from California, it would be very rare, since not much of it has been found or studied by U.S. Geological Survey's since the 1970's and when discovered, it was much more inland, Amador County near Sacramento, not along the coast lines of Big Sur or Willow Creek. Check Mindat and you'll see what I mean.............!
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Post by sntacrzrocksfossils on Jun 18, 2020 17:15:50 GMT -5
I know this thread is from a couple years ago, but i have found similar stones at Willow creek big sur, and I have had a gentleman from New Zealand with similar geology in his home town tell me it could be hydrogrossular garnet. If that material is indeed Hydrogrossular Garnet from California, it would be very rare, since not much of it has been found or studied by U.S. Geological Survey's since the 1970's and when discovered, it was much more inland, Amador County near Sacramento, not along the coast lines of Big Sur or Willow Creek. Check Mindat and you'll see what I mean.............! Pizzano, i am no expert, but an old paper from the 1960's called "Nephrite Jade and Associated Rocks of the Cape San Martin Region, Monterey County, California. mentions of there being road cuts in whitened zones containing Rodingite which they describe as a lower grade hyrdogarnet group. archive.org/details/nephritejadeasso10crip sorry just figured out how to reply to individual posts.
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Post by hummingbirdstones on Jun 18, 2020 19:58:38 GMT -5
If that material is indeed Hydrogrossular Garnet from California, it would be very rare, since not much of it has been found or studied by U.S. Geological Survey's since the 1970's and when discovered, it was much more inland, Amador County near Sacramento, not along the coast lines of Big Sur or Willow Creek. Check Mindat and you'll see what I mean.............! Pizzano, i am no expert, but an old paper from the 1960's called "Nephrite Jade and Associated Rocks of the Cape San Martin Region, Monterey County, California. mentions of there being road cuts in whitened zones containing Rodingite which they describe as a lower grade hyrdogarnet group. archive.org/details/nephritejadeasso10crip sorry just figured out how to reply to individual posts. Here is the link for the Cloudinary tutorial for posting pictures. It takes a while to get it set up, but if you follow the steps, it is then very easy to upload your photos.
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pizzano
Cave Dweller
Member since February 2018
Posts: 1,390
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Post by pizzano on Jun 18, 2020 20:10:05 GMT -5
If that material is indeed Hydrogrossular Garnet from California, it would be very rare, since not much of it has been found or studied by U.S. Geological Survey's since the 1970's and when discovered, it was much more inland, Amador County near Sacramento, not along the coast lines of Big Sur or Willow Creek. Check Mindat and you'll see what I mean.............! Pizzano, i am no expert, but an old paper from the 1960's called "Nephrite Jade and Associated Rocks of the Cape San Martin Region, Monterey County, California. mentions of there being road cuts in whitened zones containing Rodingite which they describe as a lower grade hyrdogarnet group. archive.org/details/nephritejadeasso10crip sorry just figured out how to reply to individual posts. I understand the "expert" aspect.......I don't qualify either....!
However, Garnet is a term that is not frequently used in relationship with Jade.........particularly hydrogrossular formations. More often than not they get lost in the translation....... Jadeite is not the same as the common Nephrite Jade.........there are occasions where the Jadeite will qualify as a Garnet material. However, seldom the Nephrite........... the term Jade is frequently used as it relates to a color, not so much the actual physical properties.........
Just thought for clarification sake, and to prevent additional confusion or "wild goose" chases and "bummer" let downs, a little more clarity should be recognized. As I referenced previously, the existence of/or actual recovered and mined "Hydrogrossular Garnet", based on current Geological Surveys and Mindat.Org records available to the public, appear to indicate that such material rarely appears along the surface of the California coast. Of course there could be an exception, but comparing "apples to apples" to start with is, IMHO, a better approach to rock and mineral identification.....without actual hands-on physical inspection and analysis.........Just food for thought.
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pizzano
Cave Dweller
Member since February 2018
Posts: 1,390
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Post by pizzano on Jun 19, 2020 12:47:53 GMT -5
I'd even consider the possibility of a Serpentinite formation due to it's abundance in the northern California coastal and mtn. range locations........It is BTW the States official rock.....!...........That would mean Diopside inclusions........But Jade and Garnet assumptions are a stretch, IMHO......!
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Post by sntacrzrocksfossils on Jun 21, 2020 17:07:15 GMT -5
Very cool. And those are from willow creek big sur?
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