Friends of Jade

Is there any story behind the unusual 'crystalline' structure of these jadeite bangles? These are not the only ones - the unusual type appears in other colors (white and stained yellow so far) and seems to get more respect then other opaque 'stony' types.

http://img383.imageshack.us/my.php?image=perakoi6.png

Got a few answers in the meantime; something to do with skinless jadeite boulders... Interesting.