Iris (Rainbow) Agates
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Item# HMIA05108813
Polished Horse Mountain
Iris Agate
$135.00
Quantity Available 1 each

Iris agate owes its spectral colors to the presence of a diffraction grating structure. The iris agate grating structure results
from the segregation of alternate layers having higher and lower refractive indexes during crystallization of the needles or
fibers of chalcedony.

Iris is observed in highly polished and thin cut agate (about 1.5mm or 1/16th inch) up to about 6mm or 1/4 inch. The iris is
observed by placing the specimen in front of a light source at about arms length and moving the specimen until the light
passing through the specimen reveals the spectral colors. It must be viewed at the correct angle to see the Iris effect.

"A specimen which shows primary colors in very thin section may show only pastel colors if it is cut too thick. If the line
spacing is not quite uniform only pastel colors may be seen, and if it is very irregular only a chatoyance will be observed."
The conditions for Iris to occur are quite specific. When the conditions are close but not good enough then the occurrence
is chatoyance and not Iris. Simply put, If there is not a play of color, it is not Iris.
            (quotes from American Mineralogist Vol 37 pages 578-587, published in 1952)
HORSE MOUNTAIN IRIS AGATE...ONE OF AMERICAS FINEST HIGH GRADE IRIS AGATES

This material is from closed sites in middle Tennessee and while relatively unknown today to all but some old time rock
hounds, this is some of the  WORLDS  BEST. There are two basic types of Iris from Horse Mountain and the first is the
clear to whiteish material common to all iris sites. The second is unique for U.S. material as far as we know and has a
brown body color to the agate. Other sites may have blobs of color or dendrites but not the brown body color.   Mentioned
in Judith Zeitners   " APPALACHIAN MINERAL & GEM TRAILS "   in 1968  this material has been depleted long ago.

This stone is backlit with a 40w incandescent bulb for pictures and the camera is a Nikon D40X using an 18-55 Nikon lens
and usually used with a Mercury Optics 52mm 0.45x macro lens. While viewing these pictures (taken by Rockman 836
Lapidary) please remember that the camera shows greater detail of the stone than is generally visible with the naked eye.
Please note; although we are lucky enough to have a few pieces of Horse Mountain Iris Agate to sell …do not think that
this is common material…it is not. When this stock is gone there is no more available.

THIS STONE is 1.75" x 1.25" x .1 to .125" in size. The band of iris is 7/16 " wide and crosses the stone except for the spot
on the right. It is an upper bright lower vivid level of iris in the rarer brown bodied agate and is a nice specimen for the
collector or cutter. Horse Mountain Iris Agate rivals or beats the best from anywhere in the world.
HORSE MOUNTAIN IRIS AGATE...WITH TURTLEBACK! ONE OF AMERICAS FINEST HIGH GRADE IRIS AGATES

This material is from closed sites in middle Tennessee and while relatively unknown today to all but some old time rock
hounds, this is some of the  WORLDS  BEST. There are two basic types of Iris from Horse Mountain and the first is the
clear to whiteish material common to all iris sites. The second is unique for U.S. material as far as we know and has a
brown body color to the agate. Other sites may have blobs of color or dendrites but not the brown body color.   Mentioned
in Judith Zeitners   " APPALACHIAN MINERAL & GEM TRAILS "   in 1968  this material has been depleted long ago.
This stone is backlit with a 40w incandescent bulb for pictures and the camera is a Nikon D40X using an 18-55 Nikon lens
and usually used with a Mercury Optics 52mm 0.45x macro lens. While viewing these pictures (taken by Rockman 836
Lapidary) please remember that the camera shows greater detail of the stone than is generally visible with the naked eye.

Please note; although we are lucky enough to have a few pieces of Horse Mountain Iris Agate to sell …do not think that
this is common material…it is not. When this stock is gone there is no more available.

THIS STONE is 2.5" x 1.5" x .10" in size. The band of iris is 1/2" wide. The best spot on the iris are shown at the top and
the bottom of the stone. The band actualy does go around the center of the stone but you will have to tilt at a severe angle
to get it. The level of iris is medium bright and the colors are pretty much what you see. This is an interesting specimen
due to the combination of features.  It is the rarer brown body, it is of course iris and it also has a fine display of turtleback.
All in all an unusual larger stone even though the iris is not real bright.
Item# HMIA05108853
Polished Horse Mountain
Iris Agate
$110.00
Quantity Available 1 each
HORSE MOUNTAIN IRIS AGATE...ONE OF AMERICAS FINEST HIGH GRADE IRIS AGATES

This material is from closed sites in middle Tennessee and while relatively unknown today to all but some old time rock
hounds, this is some of the  WORLDS  BEST. There are two basic types of Iris from Horse Mountain and the first is the
clear to whiteish material common to all iris sites. The second is unique for U.S. material as far as we know and has a
brown body color to the agate. Other sites may have blobs of color or dendrites but not the brown body color.   Mentioned
in Judith Zeitners   " APPALACHIAN MINERAL & GEM TRAILS "   in 1968  this material has been depleted long ago.
This stone is backlit with a 40w incandescent bulb for pictures and the camera is a Nikon D40X using an 18-55 Nikon lens
and usually used with a Mercury Optics 52mm 0.45x macro lens. While viewing these pictures (taken by Rockman 836
Lapidary) please remember that the camera shows greater detail of the stone than is generally visible with the naked eye.

Please note; although we are lucky enough to have a few pieces of Horse Mountain Iris Agate to sell …do not think that
this is common material…it is not. When this stock is gone there is no more available.

This nearly water clear stone is 1.5" x 1.125" x .10" in size. The banding is .375" wide and 1.5" long and is what I would call
medium bright at best. The pictures show very well the extent and color of the iris.
Item# HMIA02105752
Polished Horse Mountain
Iris Agate
$79.00
Quantity Available 1 each
Notice:

The Horse Mountain
Iris Agates listed on
this page are the
very last stock we
have available and
since the source was
depleted decades
ago we may no
longer have any of
this available in the
future.

We are always
looking for old stock
sources but this
mineral appears to
be unavailable at any
reasonable price.

The USA Oregon Iris
Agate is still available
but is not nearly as
pronounced or
vibrant as the Horse
Mountain Iris Agates
All backlit
Photos by
Rockman 386