What's This? #31, Can you identify this? Options

[CP]

Let's have another since we are all havin' so much fun with these.
This is one from the old family collection that had gone un-noticed in a box of rocks until yesterday. Stuck way back in a corner of a long box and buried of course. Good thing it's pretty hard.
Very nice color and clearness too.

What is it?

[CP]

Nope honey, it was just way back in the corner but it caught my eye that day.

Good answers everyone and good eye Denise, it's crystal structure doesn't look quite right for quartz.

I was thinking it was harder than it tested out to be as well...........hardness is about 4 as a metal scribe easily scratched it.

Here is another hint.............. it's a very unusual rare form of this crystal.

And another pic held up in the sunlight to show translusence. Color kind of changes as you see and is a pale blue to clear with all sides exposed to the light, but still picks up a purple "flash" when turned at certain angles.

Keep working at it, this one is a good one, the answer will suprise ya'