Post by BearCreekLapidary on Sept 29, 2004 15:49:55 GMT -5
Hello everyone,
I just had to share this with you
Have you ever seen Iris Agate before? Below are some photo's of Montana Agate with the "Iris effect phenomenon". The photo's are of the same stone ... I wish I was a better photographer ... because the photo's do not do this piece justice at all.
I will add a little history of the "Iris" Agate below the photo's.
Iris Agate:
Iris agate is a term used to describe an optical effect occurring in nearly colorless to clear banded agate, which shows an entire spectrum of rainbow colors when properly lighted. As light passes through the clear bands, the colors of the rainbow are sorted out and concentrated. Any transparent or clear agate from any locality has the potential to produce the iris effect. Consequently, very few agates will produce the iris effect. The thinner the slice of stone the better your chances of seeing the iris effect.
Agate bands are composed of silica fibers growing in virtually one direction. If these bundles of fibers and the spaces between are properly spaced, they function as a deffraction grating, bending light like a glass prism. White light contains all of the colors of the spectrum and as this light passes through the agate slice, the colors are sorted out, and one is able to see them seperately in a rainbow of seven distinct colors, red, green and purple predominating. If sliced too thick or too thin, the iris effect is diminished or is lost.
The fact that this slab of Montana agate was 5.5 millimeters thick was an extreme rarity ... as most slabs that show the iris effect are generally less that 2mm thick.
So ... what do you think about "Iris Agate"?
Have a great day,
John
I just had to share this with you
Have you ever seen Iris Agate before? Below are some photo's of Montana Agate with the "Iris effect phenomenon". The photo's are of the same stone ... I wish I was a better photographer ... because the photo's do not do this piece justice at all.
I will add a little history of the "Iris" Agate below the photo's.
Iris Agate:
Iris agate is a term used to describe an optical effect occurring in nearly colorless to clear banded agate, which shows an entire spectrum of rainbow colors when properly lighted. As light passes through the clear bands, the colors of the rainbow are sorted out and concentrated. Any transparent or clear agate from any locality has the potential to produce the iris effect. Consequently, very few agates will produce the iris effect. The thinner the slice of stone the better your chances of seeing the iris effect.
Agate bands are composed of silica fibers growing in virtually one direction. If these bundles of fibers and the spaces between are properly spaced, they function as a deffraction grating, bending light like a glass prism. White light contains all of the colors of the spectrum and as this light passes through the agate slice, the colors are sorted out, and one is able to see them seperately in a rainbow of seven distinct colors, red, green and purple predominating. If sliced too thick or too thin, the iris effect is diminished or is lost.
The fact that this slab of Montana agate was 5.5 millimeters thick was an extreme rarity ... as most slabs that show the iris effect are generally less that 2mm thick.
So ... what do you think about "Iris Agate"?
Have a great day,
John
