I know we rock and or mineral collectors don‘t like admitting this, but sometimes a rock or a mineral is just plain ugly, lacking all symmetry, boring color, nasty texture, etc. I think the ugliest rock is conglomerate and the ugliest mineral is asbestos, I hate the fibrous appearance, yuck. The prettiest mineral, in my view, is vanadinite, and the prettiest rock granite.
I've seen a lot of hematite samples which basically look like poop.
A cast iron skillet (or other cooking device). I'm not is that counts as BIG or not.
well screws, rods,manholes
For me carbonates (limestone and dolomite) are the drabbest of all rocks. I know they tell an interesting story (ie coral reefs etc) but carbs just leave me cold. As far as minerals go - anything fine grained and homogeneous is generally boring. Give me some crystals, banding and vivid color. I love labradorite and the pleochroism of the feldspar crystals. Also the pleochroism of argonite on ammonite fossils (ammolite gemstone). But to tell the truth I have never met any rock or mineral I didn't like.
