"HI Bill, great info in this thread! At Rock Candy, both fluorite and quartz occur in botryoidal habit. The hemispherical quartz always starts as sub-parallel needles, which under magnification look like a pin cushion. The prism faces are elongated to an amazing aspect ratio, 50:1 or more, so in hand specimen the crystals appear fibrous. Individual hemispheres occur to 2 inches across.
The botryoidal fluorite is an assemblage of cube faces, each sligtly rotated from the axis of the original cube. Sunagawa, in his book "Crystals: Growth, Morphology, and Perfection" (Cambridge, 2005), says such rotation starts as step dislocation on a molecular level. The curious thing to me is that the offsets appear to be random to produce a hemispherical surface.
BTW, neither of these examples formed at low temperatures ... the veins at RC are pulsed hydrothermal, and were hot enough to alter the syenite footwall a dozen feet from the vein. Perhaps there is more than one method of botryoidal formation? I'll get back to this discussion next time I'm out of the hills.
Bob
Bob"

"Here is one of my favorite botryoidals...I call it the OrcBot as I see an orc with hooves, snout and wild black hair...what do you see?

http://s790.photobucket.com/albums/yy184/jadadara/PILCHUCKCREEK/Summer09/OrcBot/?albumview=slideshow
(edit) here is one shot i posted on the wiki:
http://cash-and-treasures-wiki.travelchannel.com/photos/album/99317/Pilchuck/photo/7863092/OrcBot
~zeke"