[Rockhounds] when volcanoes drop bombs: giant crystal payload

[Tim Fisher]

Interesting, I can't find a Mac's Butte anywhere in Idaho.

At 01:41 PM 8/1/2007, you wrote:
>Most likely it is from the Cinder Butte cone SE of Spencer. Easy to 
>find, follow the road east from Spencer past the opal deposit access 
>road, when you hit the "T" turn right towards Dubois and drive down 
>to the cinder cone which is in plain sight, can't miss it.
>
>Those large plagioclase megacryst/xenocrysts are common and fairly 
>easy to find in the cinders and bombs and weathered free. A few are 
>sharp crystals, a few have large cuttable areas (typically pale 
>yellow). The identification is given as labradorite for those on 
>Cinder Butte and Mac's Butte and andesine at Crystal Butte (from 
>Earl V. Shannon, "Minerals of Idaho"). Generally the information 
>Shannon used was from specimens and work done at the Smithsonian, so 
>should be reliable. All these cinder cones are in the same area of 
>Idaho, east of Spencer and Dubois and north of St. Anthony. There 
>are more cinder cones in this region and westerly to Craters of the 
>Moon and the INEEL (Idaho National Engineering and Environmental 
>Laboratory). Some are accessible, some are not. Could be some good 
>"sunstone" prospecting for the prospector minded. Geary Murdock 
>collected several gem quality sharp yellow crystals up to about 1 
>1/2 inches 15 years ago from one of the cones. One of the many 
>things on my To Do List and I haven't gotten to exploring that area 
>yet, except for Cinder Butte.
>
>Regards,
>
>Lanny
>

Tim Fisher
Ore-ROCK-On!
Email address at http://OreRockOn.com