Would you prefer to buy jewelry made of calcite or quartz? Why (give 3 reasons)?

Question

Thanks!

Answer 1

Calcite is one of the more stable forms of calcium carbonate, and quartz is an extremely common mineral made of silicon dioxide. Out of the both of these, I'd rather buy jewelry made from quartz, and it mostly comes down to durability.

First, let's take a look at hardness. Quartz has a mineral hardness of 7, known in official terms as "very hard". Meanwhile, calcite has a hardness of 3, which is pretty soft in relation. So if you have jewelry made from calcite, you'd want to be careful to bump it against pretty much anything, because it'll chip and break off pretty easily.

Additionally, calcite dissolves in acid quite easily, putting a little acid on a mineral is one way to taste whether or not it's calcium carbonate. Even the acidity of carbon dioxide in the air or mildly acidic rain could lead to some dissolving, not something you'd want for an expensive piece of jewelry, right?

Finally, we can look at cleavage. Different minerals will cleave in different ways and directions, often giving chunks of them a characteristic shape. Calcite cleaves in three dimensions, meaning that, structurally, it is weak in all three dimensions. Meanwhile, quartz has no cleavage planes in any direction due to it's molecular structure, so it's less likely to cleave in any direction, it'd just fracture.

Hope this helps!

-Jonathan

Answer 2

That depends on what you prefer in terms of cosmetics or durability.

If you go with the cosmetics route you will find that calcite may look more pleasing to the eye because it comes in all sorts of engaging colors. However, you have to consider that according to Mohs hardness scale, it scores relatively low. This means that it can easily be scratched by any other object/mineral that has a higher hardness. It is more suitable for jewelry like earrings or pendants rather than something worn on the wrist like a watch.The reason is because it has perfect cleavage in 3 directions, so if you were to smash it with a material that is harder it would yield perfect looking rhomboids. Do not drop calcite in HCI, you will experience fizzes and a reaction you will not be happy with.

Quartz on the other hand has a much higher hardness going at about 7. Probably not as cosmetically pleasing as calcite for use in jewelry but it would again depend on what you want to wear and where you will wear it. For example, if you plan to wear a necklace made from quarts you will disappointed because it will not yield a perfect cleavage like calcite. If you are going out with friends and want to impress them with a perfect cleavage, quartzite is not the way to go. Quartz's cleavage is relatively weak, so if you were to drop it it would probably fracture across and leave some sort of scattered swirly crack. You can drop it all you want in HCI and it will not react. In this case it would make more sense to have a bracelet made from quartz or a watch that is at least waterproof.