FMF - Friends of Minerals Forum, discussion and message board

[Roger Warin]

Hello,
We are living a change of China's opening period for the past 20 years especially. In mineralogy, the finds are sometimes sublime.
So it is for the stibnite Ancient Greeks already knew. It was called platuophthalmon (large eye), as elegant women of antiquity used it as shadow of eyelids, to expand the look.
My question is more prosaic. Stibnite has elasticity in the direction of elongation, but it also breaks. I think it can have translation plans.
I'm still surprised to see this crystal bent to 90 °.
What and how do you explain this feature?
Thank you.
Roger.

[Pete Richards]

Yes, stibnite deforms readily by translation gliding. This sometimes happens naturally, and it sometimes "happens" when in the possession of a human who thinks a bent crystal is more attractive than a straight one.... In my experience, the bend is usually more like 45°, but if so, two successive bends close together would create a right angle.

[Roger Warin]

Many thanks Pete.
Roger.