Tiger Eye - What is it Composed Of?

[mirkaba]

I always thought Tiger Eye was made of tigers with the black stripes being softer than the yellow ones, or am I wrong?
Bob

:)

[James D. Farrow]

Looks like my piecce.

But even if you cabbed it that way (1/2" wide) as soon as you try
to round out the sides it will go blackish. Correct?

James

[Amethyst Rose]

The long sides where the ends of the fibers are will be darker but the top of the stone and most of the way down the sides will be either the yellow or blue of the original tigereye.  The whole stone will not go black.

Bob Johannes
The Amethyst Rose

[James D. Farrow]

Thanks!

I guess I can play with it. Nothing to lose really.

James

[Frantic Tumbler]

Tigereye is actually not a pseudomorph of quartz after asbestos.

Each fibre is in fact a quartz crystal.

[Amethyst Rose]

In mineralogy, a pseudomorph is a mineral or mineral compound that appears in an atypical form (crystal system), resulting from a substitution process in which the appearance and dimensions remain constant, but the original mineral is replaced by another. The name literally means "false form".

In the case of Tigereye, the original fibers were individual crystals of crocidolite which  have now been replaces with an individual crystal of quartz.  I thinks this meets the definition.  You could also call it a quartz replacement of cricodolite.

Bob Johannes
The Amethyst Rose

[Ranger_Dave]

Maybe not....

MinDat says this: A new interpretation of the origin of tiger's eye was recently given by Heaney and Fisher (2003): "Tiger's-eye is an attractive and popular gemstone that is ubiquitous in stores that cater to rock and mineral collectors. For more than a century, textbooks and museum displays have identified the material as an archetype of pseudomorphism, i.e., the replacement of one mineral by another with the retention of the earlier mineral's shape. Our study has revealed that the textures responsible for the shimmer of tiger's-eye do not represent pseudomorphic substitution of quartz after preexisting crocidolite asbestos. Rather, we argue that tiger's-eye classically exemplifies synchronous mineral growth through a crack-seal vein-filling process."