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Unakite or not?


#1

Hi all,

I’m about to move back to the USA from Norway, and have been coming
across what seems to be the equivalent of Unakite here in Norway for
years…It’s all over the place here, most of the rock around here
is made up of some mixture of feldspar and other minerals. Anyway…I
made a point of collecting some yesterday, and while some has the
typical olive and pink look to it, some is a MUCH darker green
epidote and salmon colored feldspar. Would this still be considered
unakite? I have pictures at

There are two samples of they typical and one of the dark to compare.
There is a 4th rock in the picture which is a feldspar/quartz/biotite
and garnet matrix I found part way to Oslo. Much of the “Cunakite” I
picked up had been crushed for filler rock on roads or in stone dumps
from construction work (tunnels etc).

Any feedback welcome. Just wondering if I should grab some more
before I move!

Jeanne
http://www.jeanniusdesigns.com/


#2

Hello Jeanne,

What you have sounds remarkably similar to some material I collected
in Scotland that we call “Iona Bloodstone” but it is more properly
called Lewisian Gneiss. I have also noted that it seems very similar
to Unakite. I could not get your web page to open, but you can have a
look at mine at

http://celtarts.com/iona.htm

Stephen Walker


#3
    I made a point of collecting some yesterday, and while some
has the typical olive and pink look to it, some is a MUCH darker
green epidote and salmon colored feldspar. Would this still be
considered unakite? 

Absolutely. Like most rocks, unakite’s chemical composition varies
with its’ exact mineral content. African emerald contains no trace
element of chromium as Colombian does, but it’s still emerald. Green
epidote with pink feldspar inclusions is unakite.

    Any feedback welcome. Just wondering if I should grab some
more before I move! 

Of course you should, Jeanne. Never pass up the opportunity for nice
gem rough of any kind. If you do, you’ll be sorry :slight_smile:

James in SoFl


#4

Unakite is defined as a rock composed of pink feldspar, green
epidote and quartz.

Some of your specimens look like they are rich in biotite but
missing the epidote.


#5

All,

It could be that unakite should have been spelled eunuchite; I’ve
never seen any that was particularly sexy. It seems to me that the
Scandinavian road departments had the right idea; a eunuchite
pavement would offend nobody except that the sound of it as gravel
might be a bit high pitched. PDQ Bach might want to write a
eunuchite cantata…there is no end to the possibilities !

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


#6

What is it in Epidote that give it the green color? This stuff seems
a bit different than the stuff from down in the south east
USA…either brighter green and pink or much darker colored green.

Jeanne
http://www.jeanniusdesigns.com


#7

The one with the biotite was another material I found east of here
which appears to be quartz and/or feldspar, biotite and a pinkish
garnet of some kind. Tonnes of it out there where they’ve blasted to
build beside the road.

Jeanne
http://www.jeanniusdesigns.com


#8

Jeanne,

I got your page to open. Your material looks exactly like the kind of
thing I collected on the Isle of Iona in Scotland. The southern half
of the island is made of it. Some is very wide bands, up to 30 cm
wide, but the best looks likes your samples that have a fine enough
figure and banding that small so that if you cut a jewelry size stone
you still have an interesting pattern. I was told that the lewisian
gneisses are some of the oldest material in the earth’s crust. The
Unakite found in Eastern US is not described as a gneiss but it does
contain all the same minerals. It would be nice someone else can
explain what makes it gneiss or not.

There is a little bit of folklore about the gneiss with especially
bright reddish tones. It is said that the red in the western sky at
sunset is the never ending battle between the fairy-folk and the
hosts of angels. None of them ever die, but the blood from their
wounds falls in the sea and will wash up on the shore as
"bloodstone".

Stephen Walker


#9

Why is epidote green?

Epidote is a hydrated calcium, iron and aluminum silicate. It is the
iron that causes its green color which can vary from dark green to
the pistachio color one often sees in unakite.


#10
     African emerald contains no trace element of chromium as
Colombian does, but it's still emerald. 

James,

Are you sticking with this statement? Whilst I have agreed with most
of what you have written to date, I am not sure many gemmologists
would agree with you on that one.

Emeralds by definition should contain Cr and in the US some
containing Vanadium are also classified as emeralds. Cibjo guidelines
state that emeralds must contain Cr to be classified as emeralds
though, so I guess we will have to disagree on that one if you stand
by your statement that African emeralds contain no trace chromium.
Samples that I have examined from Sandawana (Zimbabwe) and Zaire
definitely showed chromium absorption lines with a hand held Beck
prism spectroscope.

Re: the Unakite. Guess samples would have to be examined and
compared to samples of unakite to see if they could be classified as
such. The ones with green colouring could be classified as such, but
the others don’t look like they stand much chance since no green is
visible.

Regards - Nick


#11
    Emeralds by definition should contain Cr and in the US some
containing Vanadium are also classified as emeralds. 

If its green beryl, it ought to be emerald, regardless of WHY it’s
green. It may not be very GOOD emerald (if the color is pale), but
green beryl is green beryl is only sometimes emerald, and only then
based on some arcane criteria that you need lab equipment to
identify.

Seems silly to me. But then, being the phillistine that I am, I
prefer a good synthetic anyway. They look better, being totally
without inclusions and flaws. LOL!

Ruby is just red corundum - except that there’s apparently a move
underway (if not actually implemented yet) that wants to say it’s
not enough for it to be red, it also has to have some specific
mineral in it. Otherwise it’s “just” sapphire.

Again, seems pretty silly to me. If it’s red, and its corundum,
it’s a ruby.

Sojourner
Who know that a lot of historically famous “rubies” are actually red
spinel. Which if I recall correctly is actually rarer than ruby…


#12
         African emerald contains no trace element of chromium as
Colombian does, but it's still emerald. 

No, I’m not sticking with it. What I should have typed is that
African emeralds are typically more bluish than Colombian emeralds
due to the increased presence of iron, which illustrates the point
that the unakite in question can also vary in mineral content. It was
late when I typed the message. Thanks for keeping me honest, Nick :slight_smile:

James in SoFl


#13
   The Unakite found in Eastern US is not described as a gneiss
but it does contain all the same minerals. It would be nice someone
else can explain what makes it gneiss or not. 

If I remember correctly from high school, Gneiss is a metamorphosed
version of Granite. Usually with the grains squeezed together.


#14

I believe that the difference in African vs non African emeralds is
reflected in how they appear in a chelsea filter? Or was it under UV
light…can’t remember which and all my gemology books are packed!

Jeanne
http://www.jeanniusdesigns.com


#15

Jeanne, the stone is a norwegian unakite.

It contains green epidot and red to pink feldspat, and very often
some lines of white granite. You find it in belts and in granite
along roads, and often in pieces along rivers, rounded and quite
cute.

I have cut and polished a few, it gets a nice polish.

If you collect some norwegian stonebefore ypu leave us, do not
forget the Larvikitt (blue labrador, which they sell as Blue Pearl
for benches and bathrooms) either, it is also filled up as roadsides
around Larvik/Helgeroa/ where they have a big billion industry with
this. The stone gets a nice polish, look at it how its broken, the
glow comes best our one way. There is so much of this that you can be
really selective to find pieces with big blue glowing spots and cut
slices to bring with you.

I will tell you off list exactly where you can find very nice
excamples of the unakite, a little more than an hour with car from
where you live.

I’m sorry I do not have pictures of them both ready polished, only
some cut into pieces.

Lise
http://www.justliss.com
http://www.voringfossen.com


#16
    If I remember correctly from high school, Gneiss is a
metamorphosed version of Granite. Usually with the grains squeezed
together. 

Hm…I was wondering if that wasn’t what Unakite was while this was
more loosely packed (the stuff I find here).

Jeanne
http://www.jeanniusdesigns.com


#17

Hi Zen,

Again, seems pretty silly to me. If it's red, and its corundum,
it's a ruby.

The problem isn’t differentiating a ruby based on it’s chemical
make up. it’s telling the RED

The problem isn’t differentiating a ruby based on it’s chemical make
up, its telling the RED from the PINK. corundum. When the the value
of a stone goes up if it’s ‘red’ as opposed to ‘pink’, the red one
wins every time.

Dave


#18

Correct description from a norwegian stonemad friend of mine with a
stoneshop: He looked at Jeannes stone

This is norwegian unakitt

Green = epidot
Red = feldspatt
White/grey spots = qvarts (and granite in some cases)
black = biotite (or *crowsilver/glimmer)

Lise
http://www.justliss.com
http://www.voringfossen.com/


#19
The problem isn't  differentiating a ruby based on it's chemical
make up. it's telling the RED 

And how does one draw the line between dark pink and light red?
Especially as research suggests that we all see any given coloured
item differently.

Perhaps a quantative measure of red light absorbed/reflected is the
answer.

Pat


#20
   I believe that the difference in African vs non African
emeralds is reflected in how they appear in a chelsea filter? Or
was it under UV light....can't remember which and all my gemology
books are packed! 

That’s correct. The African stones, since they do not contain
chromium, do not show up red under the Chelsea filter.

Jerry in Kodiak