|
Post by vegasjames on Apr 25, 2022 19:53:03 GMT -5
What is the hardness and density. If you do not have a scale to test the density, does it feel relatively light for its size? If so, could be common opal. Otherwise a chalcedony.
|
|
|
Post by jasoninsd on Apr 25, 2022 20:26:35 GMT -5
Ok I feel like Schultz from Hogan's Heros, I know nothing. I'm gonna have to run out to the garage and check, hang on a minute. I'm back and nope it's about as dense as my other rocks of the same general size and I can't scratch it with a Craftsman flat head screwdriver either. This made me laugh out loud! LOL
|
|
|
Post by Peruano on Apr 26, 2022 7:19:31 GMT -5
Me. I'd like to see the other side (not the sawed side) to see if it looked like it was weathering like chalcedony/agate or like a fine grained quartzite. If it shows evidence of conchoidal fractures I'd go with the former, but if it was lots of tiny pits and a few cracks or fractures that tended to orient parallel or slightly tangentially to the rock surface (peeling like an onion) then I'd lean toward quartzite. I know agates and cherts can have bands like this rock but those kinds of bands are quite common in quartzites as well. Agate bands have real distinct boundaries because the build up slowly whereas bands in metamorphic sedientary rocks tend to be a bit fuzzier because they are originating from layers of granular material of differing colors. Your bands are going toward the fuzzy boundary stage and hence more like those in a quartzite or banded chalcedony (of sedimentary origin). These are impression and not "school book" facts.
|
|
|
Post by fernwood on Apr 26, 2022 7:20:14 GMT -5
Is it somewhat translucent?
|
|
|
Post by rmf on Apr 26, 2022 7:24:08 GMT -5
@blockhead My first thought is it could be several things. I will assume it is from TX. Make your self a hardness test kit. Fingernail H=2.5 Copper Penny H=3 Pocket Knife H=5 to 6 Quartz Crystal H=7
For this try scratching with a quartz crystal. If it scratches not agate/chert.
This could be petrified wood or chert. P Wood you should be able to see a cellular structure under high magnification.
|
|