Also known as Amazon Stone, this material is a variety of feldspar. I have accumulated a nice basket of this stone from several sources. It appears to be full of fractures and soft, but surprisingly it cuts and polishes quite well. Some pieces even display chatoyance and depth while others reveal embedded crystals.
One of those cable prospecting shows I caught awhile back showcased a family who was mining Amazonite in Colorado. They had a backhoe and dynamite and were blasting the living hell out of this mountain in search of large Amazonite and smokey quartz crystals. So, perhaps my collection came from Colorado? I don't know. I got mine from estate sales and a bag worth from a local rock show. It's one of those stones I grab a handful of now and again when I'm doing some cutting on the trim saw.