Description: If making multiple purchases, please read the note following the red text below! 0 0 0 Porcelanite from the Monterey Formation, Lake Lopez, San Luis Obispo County, California - display specimenThe Monterey Formation is a diatomaceous accumulation of sediments in basins that were adjacent western North America between 15 and 5.5 million years ago. It is a part of a circum-Pacific ring of diatomaceous sediments that resulted from major changes in paleoclimate, coastal upwelling and areas of biosiliceous productivity that occurred at that time. Intensified coastal upwelling resulted in high plankton productivity and rapid deposition of siliceous ooze from the constant rain of dead diatoms and radiolarians falling to the sea floor. The sediments that accumulated farthest from the coast were primarily calcareous and siliceous. These sediments were rapidly and deeply buried. During diagenesis, the biogenic silica dissolved and reprecipitated as more stable opal and eventually, with time and increased temperature, forming porcelanite, chalcedony and chert. Diagenesis refers to the conversion of sediments into sedimentary rock. Where clay is a larger component of the sediments, diagenesis forms porcelanite, which has a silica content of 50 to 85%. With a silica content of 90% to 95%, the rock would be chert. The Monterey Formation is the source rock for most of California’s petroleum production. The field photo shows tilted beds of porcelanite in the Monterey Fm. near Lake Lopez. Select a specimen: When more than one specimen is shown, you can select a particular specimen by telling us what is in the photo with it - a black mechanical pencil, a silver and black pen, a silver and blue pen, or one of those plus some number of coins, or you can let us make the selection. Making multiple purchases?Just add items to your cart. When finished shopping, click on “request total” at upper right in the Shopping Cart window. Do not proceed to checkout. We will send an eBay invoice with the correct combined shipping. The combined shipping will often be less than eBay shows. Please wait for that invoice before paying. There is no obligation to purchase. You can decide after seeing what shipping will cost.Shipping: Priority Mail or Ground Advantage, whichever is cheaper, unless we can find a better rate. Rates vary by weight and zip code. We can ship for less than eBay will charge, and will refund the overpayment as soon as the box is packed. International customers: We sell and ship internationally. If eBay’s page does not let you enter your country name to determine the shipping cost for something you are interested in, please contact us. We can tell you what the shipping would cost and how to make the purchase. You can then decide if you wish to complete the transaction. Use the Contact Seller link in the Seller Information box on the right side of this page. Pay securely with your debit or credit card through PayPal! You do not need a Pay Pal account to do this. Yes, we do combine shipping!
Price: 13.75 USD
Location: Olancha, California
End Time: 2024-08-22T07:15:33.000Z
Shipping Cost: N/A USD
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Return shipping will be paid by: Seller
All returns accepted: Returns Accepted
Item must be returned within: 30 Days
Refund will be given as: Money Back
