Topaz is a very popular mineral and gemstone, particularly for use in jewelry. Most nice crystals come from various pegmatite pockets around the world and are highly sought by mineral collectors. Finding topaz is quite tricky quest - and even more tricky is faceting topaz into gems.
Quartz is an incredibly common mineral that can manifest itself in all kinds of environments. It forms a very beautiful crystals, and it is highly versatile, as it comes in many different colors that go by several names.