colormyworld
Brilliant_Rock
- Joined
- Aug 30, 2005
- Messages
- 1,172
The C- axis is down the lenth of the stone. As most of those crystals are laying on thier side with the A or b axis showing how does that show the difference between an open and closed c- axis? I just see some crystals with much lighter tone than others. Can you please explain how that picture shows the differnce between an open and closed c-axis?Date: 9/12/2009 9:32:18 PM
Author: tourmaline_lover
THank you again MTG.Date: 9/12/2009 9:24:13 PM
Author: MakingTheGrade
Thanks TL, I guess I'm just trying to figure out what it physically means (in terms of light optics) to have a 'closed axis'. Like, what is it that causes it to be closed from one axis and not the other? Is it like a polarizing filter affect somehow?
Haha, maybe my science background is not strong enough for this. Anyhow I hope this one is nice and open and pretty I have long admired your cuprian and stepcutnut's lovely nambian blue tourmaline!
I think a picture speaks a thousand words when trying to convey the difference between open and closed color. Take a look at this selection of indicolites. It's easy to see which are 'closed' and which are 'open.' I hope a lapidary chimes in here to give a better explanation than my attempt though. It has to do with the fact that tourmaline is dichroic. Again, my attempt to explain this phenomenon is feeble next to some people I know (who I hope chime in). I know people that attempt to describe this at the atomic (quantum) level!!
BTW, your stone looks definitely open. I would be shocked, based on the pictures, if it went dark in certain lighting.