Unkown Yellow Crystal/Mineral ?

TJE · Mar 13, 2013

Hello,
I found this stone 20 some yrs ago. I was high up on the banks of a large river (Northern-Alberta) hunting for fossils, bones etc, it was the shape and half the size of a small egg. On the outside it looked like white quartz? but after holding it up to the sun...I could see the faint yellow center (just like a yolk in an egg)..so I shattered it open between two large stones, puzzled by the interior I kept the pieces...dremeled a few to try and smooth/shine the yellow with a diamond bit (which got so hot it glowed) pretty much demo-ed that bit.
it easily scratches glass. Anyones knowledge would be much appreciated.
(sorry for crap pics)
TJE

Bajahunter · Mar 13, 2013

Could be opal. The broken pieces look right.
Does it scratch a piece of quartz.
Opal is softer as it has more water but both are silicon dioxide. Fossilized corals and trees can be opal as well as chalcedony. So possibly it is a fossil.
If it is same hardness as quartz then it would be called carnelian.

TJE · Mar 14, 2013

Hey Bajahunter, thanks for the info.
The white outer/exterior is quartz I think...and yes, the orange/yellow interior does scratch it.
I do have fossil corals, bracs, gastros, nautiliods/ ammonite , petrified wood, leafs, etc. from the same area,
so I honestly don't believe this to be fossil/opal...but just a guess?? :icon_scratch:

TeAra · Mar 15, 2013

looks almost like yellow agate

TJE · Mar 15, 2013

Hi TeAra, Thanks...will have a look.
Do you know if yellow/agate is hard enough to do damage to a diamond-tip Dremel bit?
Thanks

TeAra · Mar 15, 2013

Depends on how good of a bit it is. So far I am on my second dremel due to stones and I eat through bits like nothing even on agate and quartz. My diamond coated saw blade even has a hard time cutting through the agates I have and I used up 2 diamond coated disc on grinding.

TJE · Mar 15, 2013

TeAra said:
Depends on how good of a bit it is. So far I am on my second dremel due to stones and I eat through bits like nothing even on agate and quartz. My diamond coated saw blade even has a hard time cutting through the agates I have and I used up 2 diamond coated disc on grinding.

Ok Thanks, had a look at the yellow/agates and see they can be drilled through for jewelry, but...this stuff seems like it would just chip from being so hard! :icon_scratch:

Thanks Again.