Think crystal-clear or yellow, as a beginning; a quartz crystal with cloudlike "flaws" is a great (and inexpensive) start. Quartz pebbles are common in pea gravel roads and playgrounds, too, so you can start with that for free.
Think red, orange, or of associations with blood, war, passion, etc. Carnelian is a great fire stone (its own associations are with blood, passion, and the heart, and it's a fiery red-orange in color). Other options include obsidian and other volcanic products -- they've been there!
Think blue, or of associations with the emotions. Sedimentary stones, formed in water, seem to recall the element well. Visit a watery place -- river, pond, whatever is close, and see if you can find something good just under the water near the shore. You might even find a sedimentary bit with a fossilized aquatic animal in it (mussel shells are pretty common, actually, once you start to look), which is what I use. (Aquamarine is an obvious water stone, but very expensive!)
The color for earth, for many people, is green, and many of the stones associated with earth are green as well. Metallic colors also find their way here, because of the association with money. Of course, any stone is an earth product, so this is a great place to put the stone you find that you want to use but don't know where, at least until you figure out what to do with it! Malachite is a very pretty earth stone, and some folks like pyrite because of its blocky structure (cubes also call to mind the Earth element.) I do use malachite on occasion, but honestly, I prefer a plain brown "rock" (never mind the identification; you don't need it for this one!) that's about as down-home "earthy" as you can get, and with enough personality to draw attention to it on a walk through the woods!
Here's one category where people will often disagree. I do like amethyst here, and many clear crystals (quartz, even selenite, etc.) seem to belong here as well. Turquoise, too, is so multi-functional that I put it into this "integrative" category. Definitely trust your intuition here!
Originally written by Weavre (A.K.A.: Jacqueline M. DeVries)
Recopied with permission.