The mortar mix on our House

I am a notorious rockhound. I'm the one person on the group hike who is always looking down at the rocks.
I thought about Geology as a major but worried I wouldn't have enough field work.
Quartzose Sandstone: Sandstone, mica, feldspar.
Over millenniums, the scattered iron-rich minerals in the sand disintegrate and the iron is oxidized into hematite crystals that form as very thin coating on the quartz sand grains. The hematite crystals absorb all light colors except red which they reflect, giving the sandstones their red color.
This fine specimen was hand picked by me on a walk along a river bank.