kellyj
starting to spend too much on rocks
Member since December 2013
Posts: 100
|
Post by kellyj on Jan 16, 2014 2:16:42 GMT -5
Hello, This rock is as hard as an agate (I did a scratch test with a pin: no marks), has some very small quartz crystals in it. What do you think it is? Back:
|
|
herchenx
Cave Dweller
Member since January 2012
Posts: 3,360
|
Post by herchenx on Jan 16, 2014 2:23:46 GMT -5
looks like either agate or jasper to me.
|
|
alan
starting to spend too much on rocks
Member since December 2013
Posts: 111
|
Post by alan on Jan 16, 2014 13:53:54 GMT -5
Chert?
|
|
Fossilman
Cave Dweller
Member since January 2009
Posts: 20,685
|
Post by Fossilman on Jan 16, 2014 17:17:02 GMT -5
|
|
garyboothe
off to a rocking start
Member since January 2014
Posts: 3
|
Post by garyboothe on Jan 17, 2014 19:38:42 GMT -5
It looks like a form of microcrystalline quartz, either the chalcedony/agate group or the jasper/chert/flint group. Because of the light color, I would guess chalcedony or agate (I would call it agate if distinctly banded, or just chalcedony if not banded). I would check the translucency to make sure it is chalcedony/agate. One way to do this is to get in a dark place and hit the rock with a laser beam from a laser pointer; if the rock or part of the rock glows, I would call it chalcedony if no banding is visible, or agate if banding is exhibited. If the rock doesn't glow at all call it jasper. Jasper, chert and flint are opaque due to impurities, whereas chalcedony/agate are always translucent to some degree.
|
|
|
Post by Starguy on Jan 18, 2014 21:33:47 GMT -5
I'm pretty sure that would be called chert. Agate, jasper, chert petrified wood, and even opal are all called chalcedony or cryptocrystalline quartz. You are very lucky to have so many sources of good material near you. Good collecting opportunities are rare and getting rarer.
Later.
|
|
|
Post by tandl on Jan 19, 2014 12:08:03 GMT -5
Chert with quartz crystals , may have some pure chalcedony in it . You may find some chalcedony nodules if your finding chert like this . this chert and many others are plentiful here in central Illinois ,some with plume and some banded agate in the chert-blue , gray,white colors. i find chalcedony nodules too
|
|