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Rutile peridot?


#1

Hello, dear Orchidians,

For the Rockhounds and anyone who might know: have any of you heard
of peridot containing black rutile? I am thinking that the stone I
am seeing is a dyed quartz, but don’t want to discount the
possibilities…

Thanks so much for your comments,
Nanette Kroupa


#2

Nanette,

Are you sure it’s not prehinte with tourmaline crystals? The color is
not quite the olive green color of peridot. I have seen many such
stones on Ebay.

Steve Brixner
www.brixnerdesign.com


#3

Hi Nanette,

For the Rockhounds and anyone who might know: have any of you
heard of peridot containing black rutile? I am thinking that the
stone I am seeing is a dyed quartz, but don't want to discount the
possibilities... 

If you have access to a refractometer, you could check the
refractive index of the stone. If it’s quartz it’ll be 1.54-1.55. If
its peridot it’ll be 1.65-1.69. You could also check the specific
gravity. quartz is 2.66, peridot is 3.34.

Dave


#4

It occasionally occurs like that in the Adirondacks of New York.

Judy Shaw, GJG formerly from the Adirondacks


#5

black is more probably tourmaline than rutile. and it can occur.

john


#6

I checked my “Photoatlas of Inclusions in Gemstones, V.2” by John
Koivula. He shows several photos of peridot from Pakistan which have
black to very dark brown needles, not rutile, but similar looking,
the minerals ludwigite-vonsenite. Could be what you have.

The colors of Peridot are pretty distinctive, haven’t seen any dyed
quartz that color.

If you examine the stone in question at 10x, looking thru the stone
at the back facets, you will see much more extreme doubling of the
facet edges in peridot than you will in quartz. Peridot is noticeably
birefrigent-- some stone will look “fuzzy” face up because of the
strong doubling effect. It may help to have a known sample of quartz
to compare. Other more positive tests are refractive index and
spectrum.

Jim Sweaney, CGA, FGA, GG
mardonjewelers.com


#7

Is it a faceted stone or a bead? I have seen peridot colored beads
with Tourmaline needle inclusions in them, and if this is the case,
you do probably have a dyed stone. The beads I saw were large nugget
type. Just a thought.


#8

I have seen peridot colored beads with Tourmaline needle inclusions
in them, and if this is the case, you do probably have a dyed stone.

My wife knows about beads says she thinks what is being discussed is
prehnite with epidote crystals. I have seen quite a lot of peridot
and it can be included, but I have not seen peridot with included
needles or other crystals. I have some of the finest peridot from
Pakistan, collected by Dudley Blauwet of Louisville, Co. The mine is
at 17,000 ft. and Dudley trains for triathlon to be able to travel
to that altitude…

At the presentation he made at the Gemological and Mineralogical
meeting several years ago he showed slides of a miner hanging by a
basket off the face of a cliff to do the mining. I do not believe
peridot can be dyed.

Richard Hart G.G.
Jewelers Gallery
Denver, Co.


#9

Check the refractive index if you would like to know for certain.

KPK


#10

I’m wondering if your beads might be Actinolite, that can be quite
green and has rutile like inclusions. Just a thought.

Candy


#11

Most likely what you’re seeing is peridot with Ludwigite needles. It
is mined only in Pakistan and is not common, especially if it is
clean with largish ludwigite crystals. I’ve cut some of it and found
it a lot of fun, very attractive, and very much in demand. I
originally thought it was peridot with black tourmaline. I may have
a few more pieces of rough, but am still recovering from my studio
fire so am not sure where everything is.

Fortunately, after 5 weeks, I got a check from my insurance company
and got my building put back together with a wall and roof last
Thursday. We did the final work in the snow and had the freezing rain
that knocked out power in the northeast on Friday. I didn’t lose
power and I now can start the interior walls, shelves, benches wiring
insulation and etc so that before too much longer I can start
thinking about working on stones again. I’ve nearly forgotten what
that feels like.

Replace your cheap power strips folks.

Derek Levin
www.gemmaker.com


#12

The oxygen fugacity of peridot is wrong to form rutile inclusions.
They are more likely to be chromite or magnetite. these will take on
a fibrous appearance but the crytsals are really dendrites. I have
seen peridots from Libya and southern Africa like that but they are
not usually big enough or clean enough for commercial extraction.

Nick