Prehnite

 I believe Prehnite is a highly underrated mineral, in particular for those that are in Namibia, South Africa and the Northern Cape.

Also I have been seeing more and more cut material in the past two years - hardness is 6 - 6.5

check wiki http://www.youtube.com/watch?v=bWhtkkOYoxo

 One of my favourites

 Prehnite + Quartz through the Center of botroidal Aggregate

 Above picture feat. front and back of a very light amethyst that has a prehnite overgrowth - Namibia - Brandberg area.

 These are just a few specimens - mostly from Namibia and Northern Cape - check Mali material tends to be more yellowish green -

Prehnite + Quartz

Mali specimen - video of Prehnite and Epidot

http://www.youtube.com/watch?v=yyCKOB34zsQ

http://www.youtube.com/watch?v=neSvUtzuu20&NR=1

It seems asif the majority of Mali specimens are a bit more yellow - than those from Namibia and Northern Cape  -