The word “rock” doesn’t normally conjure up images of beautiful jewelry, but as I explained in my very first blog post (https://mochisgifts.com/2014/06/05/gem-vs-mineral/), some rocks are also considered gems. While many minerals meet the criteria of beauty, rarity, and durability to be considered gems, very few rocks do.

Because the conditions under which rocks form can vary greatly, there can be very different looking results. Even within a specific type of rock, although the main mineral components are the same, trace elements or other minerals, sizes of individual grains, relative amounts of each mineral, and more, may differ. Causes for these differences include: the elements available in the melt source, temperature, and pressure. Most of the rocks used as gems have individual minerals that are visible to the naked eye, but some, such as basalt (sold as “lava”) have mineral grains too small to see. This variability is part of the beauty of the rock, but can also make it very difficult to match pieces for jewelry.

Enjoy these examples of rocks that are gems – I’ve listed the main constituent minerals.

So yes, we geologists love rocks, but now even non-geologists have a reason to enjoy them too!