Back to Ganoksin | FAQ | Contact

Obsidian


#1

Hi all, I recently purchased some obsidian rough from Arizona, USA.
Upon cutting into it, i discovered that it has clear layers running
through it. The clear layers appear to be quartz. When viewing a
slice of it against a light source, it looks much like a high
contrast black and white photo of wood grain. I did investigate this
stone on the inernet, but found no references to this type of
makeup. Has anyone else seen this? Any particular pros or cons? I
think if i can cut it thin enough, this characteristic could be
exploited using an open back bezel, bracelet, etc. thanks. steve

In Oklahoma where the weather is what we call Indian Summer


#2

Hi it sounds like you have apache tears.

ROBERT L. MARTIN


#3

I haven’t seen the clear layers in plain black obsidian, but i have
in mahogany obsidian. i think the clear is just colorless obsidian
not quartz. it does make a wonderful effect for lapidary.

cathy


#4

Steve - Your clear layers are obsidian, too! There are many different
appearances for obsidian; some are totally opaque, some are
translucent to transparent. The latter sort often have glass-clear
layers interspersed with pigmented layers. It is a fascinating stone.

Jim Small
Small Wonders Lapidary


#5

Another name for obsidian is volcanic glass. I guess you could call
it a stone where the structure is about the same as glass. The
minerals have not crystalized out. In much obsidian you have what
are commonly called flow lines. The composition varies a little in
these different layers, sometimes there are silvery or gold sheens
or even peacock effects in them. One rockhound name for the type of
obsidian with clear stripes and dark stripes is “midnight lace”. I
have seen pictures of cabs using thin slices of it two different
directions to produce a plaid effect. A very reflective backing might
bring out the variation better than an open back bezel. Rose Alene
McArthur In Idaho where it is going to freeze tonight and I had
better run out and cover up my squash.


#6

Steven,

Hi, I am a lapidary and been a rockhound for a longtime. The obsidian
you purchased is referred to as “Midnight Lace Obsidian”. It’s
usually slabbed up to make display pieces with a back light to show
the contrast. Sometimes it gives an almost shadow effect like or
parallax found in very good fortification agates. If you cut it
thin, obsidian is glass. In order for the design to show thru your
doing to have to have an open back. Maybe building up the back would
be good to protect it. Not good bracelet material, buckle material or
ring though. It scratches easy and chips. I dont use it in my
lapidary work or my jewelry for that reason. I also have a thing for
expensive agates =)

So the pros; it works easy, is soft, polishes great with Tin oxide.
Looks nice - lots of folks like it. Cons; the scratches, the chips,
fractures, having to cut it thin and then the danger of it being thin
from breaking etc, if mounted must have an open back, but must also be
well protected from any use the wearer might subject it to.

I have a pendant and the first time I wore it it scratched. It had a
very high dome and when I leaned over i scratched it with out even
knowing. So make it os they wear high on the neckline as well for
pendants. Feel free to email me offlist with any questions you might
still have about the rock if you have any.

Goodluck.
Jane


#7
   I haven't seen the clear layers in plain black obsidian, but i
have in mahogany obsidian. i think the clear is just colorless
obsidian not quartz. it does make a wonderful effect for lapidary. 

Banded clear/black Obsidian is not common but some really nice
material comes from the Davis Creek area in Northern California and
is called “Midnight Lace”. When it is mixed with mahogany gold sheen
it can be spectacular, especially when slabs are cut thin and used
in lamp shades.

Dick Friesen


#8
    So the pros; it works easy, is soft, polishes great with Tin
oxide. 

Steven, I agree with everything Jane says except for the polishing
medium. Tin oxide will do the job but I use the glass industry
standard…cerium oxide. You can use the cerium on a number of
carriers such as soft felt (hard felt tends to burn the stone), soft
leather or my favorite…hard leather. This puts a very high polish
on obsidian in little time at little cost. Sorry Jane…guess we
all have our own preferences.

Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry! @coralnut2


#9

I really doubt that your material is a mix of quartz and obsidian.
I’ve worked with material like this before; it’s uniform in hardness
but the black is swirled interestingly through the clear volcanic
glass. (This was likely caused by bunching and folding as the
differently pigmented layers of hot glass were extruded from a
volcanic vent). “Mahogany” obsidian is similar, but it has brown
tones in addition to black and clear. It’s not especially easy to
polish, I found, but it is pretty if set in such a way as to let
light shine through. A backless bezeled earring setting would be an
example. Another approach would be to back it with something white,
so it wouldn’t need to be held up to the light for the “grain” to be
seen.

Andrew Werby
www.unitedartworks.com


#10

Steve, I have cut this type of obsidian before. I don’t know if it
has a specific name, but it is just volcanic glass. Clear glass and
black glass, swirled together to form the “woodgrain” pattern you
mention. I have used it in doublets with clear quartz so I could
grind the obsidian layer very thin to allow enough light to pass
through without fear of it breaking. Contact me if you need any
clarification on this process.

Best Regards,
Jim DeRosa


#11

Hi All, and thanks for the responses to my questions. It makes sense
to me now that the clear layer is not quartz, but merely a clear layer
of volcanic glass. I’ve cut and faceted a fine cab about .75 inch
square by .25 inch deep, and put a really high polish on it with
cerium oxide via leather pad. It’s gorgeous! I think my next one
will be a doublet or triplet for protection and effect.

thanks again Steve Get Postal! Lance Armstrong and the US Postal
Service bicycling team are faster than your local mail delivery!