I found this while surfing a little today - I'd forgotten I'd done this!
Opal Lava Technique
The link was on the Pipedreamink Blog.
(I used to be on the design team before my life fell apart!)
Love my opals and this has inspired me to use them even more! so watch out for some tutorials and links...
Oh - and if anyone knows how to get a slideshow of their art working on blogspot - can you help me please????? firstname.lastname@example.org