This rock is a rusty yellow on the outside and white crystalline on the inside. I am just assuming it is quartz. I chipped off a little corner of it and checked on search engines to see if I could find a match, and the closest I could find was quartz. Is it rare? Is it valuable? 27 pounds!
Hornblende. Quartz is the most resistant. Generally darker/deeper minerals are not use to surface conditions and weather faster.
