When we lived in Maine I spent the better part of a long day digging out a chunk of quartz about half--3/4 the size of an old Volkswagen. Took all that I had in equipment and my 95 HP loader tractor to get it up to the house. Why, I'm not sure but it was a nice spring day. Just as I dumped it in the yard my wife yelled "get it out of here" but the ground was so soft--and the rock so heavy--that it stayed there until we left.
To my wife's disbelief, I sold it for pretty good money. I told the buyer to bring a heavy trailer but he showed up with a snowmobile trailer. I didn't want to load it but he insisted. As he was inching down the road we could see the back wheels start to splay out from the axle bending.
The quartz was great and I brought a couple 200 to 300 lb pieces of milky quartz with us when we moved just for the memories.