4. While trekking in the granitic San Gabriel Mountains near Los Angeles, CA, you find an interesting mineral (see pictures below). It has a vitreous (glassy) luster, pinkcolor, and you can

see two distinct cleavage angles. You cannot scratch it with a copper penny nor glass plate, but you can scratch it with a steel nail. The sample you found is particularlyneat, but you also notice that the granite rocks around you have a lot of this mineral in them. What is the name of this mineral? How did it form?