M543 - Known as "TV Rock" or "Mystery Rock", this rare evaporative mineral has a pearly opalescence, with unusual optical properties due to capillary fibers, clearly visible from the side.

Ulexite is a hydrated sodium calcium borate hydroxide, a mineral occurring in silky white rounded crystalline masses or in parallel fibers. Ulexite is a very soft mineral of only 2.5 on the Mohs hardness scale, about the same as your fingernail.

The fiber-optic effect is the result of the polarization of light into slow and fast rays within each fiber, the internal reflection of the slow ray and the refraction of the fast ray into the slow ray of an adjacent fiber. An interesting consequence is the generation of three cones, two of which are polarized, when a laser beam obliquely illuminates the fibers. These cones can be seen when viewing a light source through the mineral. Ulexite decomposes in hot water.

A polished face will project an image through to the other side, seeming to magnify it. It is not just a clear rock.

If you move your head slightly, you can see that you are not merely looking through the rock, the image is actually on the top surface of the rock!

 SPECIAL BUY

We have two sizes available:

A - about 2" - $9.50 each

B - about 1.25" - $5.50 each