Mineral Eggs

A mineral egg is an egg carved or cut from a naturally occurring substance that is formed through geological processes (sedimentary, heat, pressure, etc.). A rock is generally a combination of minerals and need not have a specific chemical composition. Therefore, rocks can be one mineral if they are massive, but are more commonly several minerals. Mineral and rock spheres can be handcrafted or machine cut, depending on the material.

Click here to see the beautiful and unique mineral eggs Oakrocks has available!

Mineral and rock eggs can be transparent (mostly clear), translucent (light shines through), or opaque. If a mineral egg is transparent, the clearer it is the more valuable it is. Mineral eggs also have different luster or shininess. The luster of a mineral egg can be metallic, adamantine (sparkly), vitreous (shiny like glass), resinous (semi glossy), pearly (has a iridescence or glow), chatoyant (has a glowing effect when you roll it like a light moving across the surface), or silky (fibrous).

The difficulty of cutting a mineral egg usually depends on the minerals hardness. Everyone has heard of the Mohs scale, designed in 1822 by a German mineralogist named Friedrich Mohs. He determined that diamond is the hardest mineral known to man (10), and that talc is the softest (1). His scale is ordered so that any of the minerals can be scratched by the ones above it, and in turn they can scratch the ones below it. The difference in the hardness is not necessarily equal (say from 10 to 9 may not be the same as from 5 to 4). The scale is:

10 Diamond

9 Corundum

8 Topaz

7 Quartz (the most common rock found, and generally considered the end of the “hard” rocks-cutters refer to the rest of the materials as “soft” stones)

6 Feldspar

5 Apatite

4 Fluorite

3 Calcite

2 Gypsum

1 Talc

If you are trying to identify your mineral egg, you can buy inexpensive kits with items to test hardness, or you can use household items. A good steel knife blade is a 6, glass is a 5.5, a copper penny is a 3, and a fingernail is about 2.5. And by the way, hardness has nothing to do with toughness. Diamonds can be broken, and when rockhounding some rocks can be broken very easily, others you’ll really have to work at! Jade is the toughest rock there is.

There are a wide variety of mineral eggs available. Some materials are very common and easy to find. Other mineral spheres are extremely rare or even one of a kind! Start collecting yours today, or buy some as unique and thoughtful gifts.