Joined: Sun Oct 16, 2005 12:22 pm Posts: 21602 Location: San Francisco
I suspect it is a reddish chert. This rock is common in the Franciscan Complex, along coastal California. In the case of the red chert found on our coastline, the reddish tone is the result of a small proportion of iron rich deep-sea clay, the very finest sediment that settles to the seafloor far off shore. Due to geosynclinal uplifting the chert rises to form very large outcrops here.
Joined: Thu Nov 17, 2016 11:11 am Posts: 43 Location: Northwest USA
Barbra Voltaire wrote:
I suspect it is a reddish chert. This rock is common in the Franciscan Complex, along coastal California. In the case of the red chert found on our coastline, the reddish tone is the result of a small proportion of iron rich deep-sea clay, the very finest sediment that settles to the seafloor far off shore. Due to geosynclinal uplifting the chert rises to form very large outcrops here.
Anyone else have a thought?
Spot on Barbra, this type of chert was used extensively by native americans for arrow/spear heads.
Joined: Wed Nov 15, 2006 9:44 pm Posts: 1079 Location: Washington State
I was going to say,"jasper", but then ran across this: https://www.mindat.org/mesg-7-245968.html Check out the comments section as it's a funny collection of rock nerds arguing over a name. Good thing gemologists don't do that.
Yeah, the whole chert/flint/jasper/agate/chalcedony nomenclature issue takes on different meanings in different contexts and gets really messy really quickly. Best to sidestep it entirely in most cases.
so if polished it will become a big shiny jasper? any idea how much it would lose from its size and weight by making it a Jasper? I believe it weighs around the 10kg. would you recommend doing so? Thanks
Where is it from? If Arizona, it might be jasperized wood.
It's was actually found in Israel at the mid 70 I believe in the "Eilat Mountains". we kind of like it the way it is I just wondered how much it would lose from its size by sending it to polish.
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