Applying to join this forum, you HAVE to activate your membership in YOUR email in the notice you recieve after completing application process. No activation on your part, no membership.

Lapidaryforum.net

Please login or register.

Login with username, password and session length
Advanced search  

News:

Welcome new members & old from the Lapidary/Gemstone Community Forum. Please join up. You will be approved after spam check & you must manually activate your acct with the link in your email

Congratulations to Bobby1 and his Brazilian Agate Cab!

 www.lapidaryforum.net

Another cabochon contest coming soon!

Pages: [1]   Go Down

Author Topic: Puget sound beach cobbles  (Read 1907 times)

0 Members and 1 Guest are viewing this topic.

Rustycat

  • Jr. Member
  • **
  • Offline Offline
  • Posts: 87
Puget sound beach cobbles
« on: October 07, 2018, 09:36:53 AM »

Thought I'd ask the good folks for their opinion of the following two cobbles I found on the beach.  So, thanks in advance!
45144213501_de0ac8cae6_k.jpg
*45144213501_de0ac8cae6_k.jpg (429.36 kB . 2048x1152 - viewed 377 times)

30205952207_887281710a_k.jpg
*30205952207_887281710a_k.jpg (434.61 kB . 2048x1152 - viewed 382 times)
Logged

lithicbeads

  • Administrator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3214
Re: Puget sound beach cobbles
« Reply #1 on: October 07, 2018, 09:53:52 AM »

The first is an iron stained porphory, possibly diabase.The second looks like a chert that was being down metamorphosed when i8t stopped changing. The inclusions give it away .
Logged

Rustycat

  • Jr. Member
  • **
  • Offline Offline
  • Posts: 87
Re: Puget sound beach cobbles
« Reply #2 on: October 07, 2018, 10:13:14 AM »

lithic,
I had hoped you would reply, so thank you.  I'm trying to understand your comment, and in my effort to do so, I went to https://www.tulane.edu/~sanelson/eens212/typesmetamorph.htm
Which to the lay-student's eye seems to be offering a well-developed background to understanding your reply.
BTW, the tulane link will probably take me several weeks of daily reading for me fully wrap my head around.
Logged

lithicbeads

  • Administrator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3214
Re: Puget sound beach cobbles
« Reply #3 on: October 07, 2018, 08:16:37 PM »

The problem with geology is that the pictures never match the reality of the areas outside the area the pictures were taken in. Very frustrating.I got around this problem by getting local field guides off the internet and going to the spots and seeing our local version of the rock type.Then I read most of the masters degrees in geology from WWU and many of the phd dissertations from the UW and went in the field to see the samples.Not much stuff is on the net now. Stuff that used to be free you now have to pay for but let me think about  it.
Logged
Pages: [1]   Go Up
 

Page created in 0.116 seconds with 33 queries.