Good online & free resource to learn 101 on geology, rocks and mineralogy?

Courses I look up veer more into geology from a climate perspective, but I just want to learn more about solely rocks and minerals. For context, I'm a rock climber, I just want to learn more 101 about all the rocks I touch. I.e. Sandstone, wingate, patina, pegmatite, granite, gneiss, basalt, limestone, conglomerate, quartz, marble. Any suggestions? :)