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Identifying an agate slab


#1

Is there someone out there who knows agates? I found this slab at a
garage sale – have had no luck looking in books to identify it ( is
there even such a thing as a book that identifies agates ??)

Here is the picture:

I never see this stuff at eBay – is it rare ? Or is it just there
in a degraded form? This is clearly agate - it is semi-transluscent
in the green areas.

Thanks in advance
susan


#2

Looks a bit like Parrot Wing Jasper, not agate. Is it translucent? I
can’t tell from the picture. If it is indeed agate, I don’t have a
clue.

Lisa, (Watched the Oscars…why?) Topanga, CA USA


#3

Dear Susan,

Wow ! After many decades of rock licking and other rockhound madness
I will have to confess that I have never seen anything like your
slab. The orangish dendritic pattern suggest native copper and the
chalcedonic areas suggest agate with microsopic chrysocolla
coloration. The dendrites may be pseudomorphs after native metal
growths. The same form can be observed in native silver. It is
entirely possible that it came from the Keewanai Peninsula in
Michigan, but may also have come from somewhere in Arizona. Thanks
for sharing your find with us…

Ron MIlls, Mills Gem Co. Los Osos, Ca.


#4

Susan -

Yes, there are books for agate identification; also web sites
devoted to it. My suggestion is to check these two sites

http://www.agateswithinclusions.com
http://csd.unl.edu/agates/agatepageintro.asp

The slab which you purchased is similar to several pieces which I
have seen from New Mexico, although that is no guarantee your piece
is from that state. Agates are essentially infinite in variety, as a
quick tour of either of the above sites will illustrate. Sadly, even
though many varieties are relatively (or even absolutely) rare,
agates scarcely ever command huge prices. Those which are reasonably
expensive remain bargains when compared to many other gems and
minerals used in jewelry.

You found a good one!

Keep on rockin’

Jim Small
Small Wonders Lapidary


#5
Looks a bit like Parrot Wing Jasper, not agate. Is it translucent? 

Yes the green part is translucent - the orange is opaque - some of
the dendritic parts look metalic when polished. I wonder is there
such a thing as parrot wing agate : ) ?

susan


#6

I may way off, but I’ve been told (by someone who should know) that
the difference between agate and jasper is that parts of agate can be
translucent, whereas jasper is opaque and that they are both
chalcedony. Simon & Schuster’s Guide to Gems and Precious Stones
identifies both agate and jasper as chalcedony but doesn’t say
anything about translucency.(sp?)

Jan
www.designjewel.com


#7

it is a bit hard to tell from a photograph, but appears to be

a) chrysacolla/w minor calcite over native copper and/or cuprite in
quartz, best guess north side of ray arizona pit, about 1965, or

b) northern chihuahua, mexico sagenite agate, about 1955

regards
Mark Zirinsky, Denver


#8

Hi Susan

Yes the green part is translucent - the orange is opaque - some of
the dendritic parts look metalic when polished. I wonder is there
such a thing as parrot wing agate : ) ? 

I have not heard of Parrot wing jasper but parrot wing chrysocolla
is a type of agatized chrysocolla that comes from Mexico. It is
usually shades of green and turquoise occasionally with a little
yellow. I have not seen any with the red/orange you have in your
slab.

Karen Bahr
Karen’s Artworx