Is Labradorite a Crystal or a Rock?

Labradorite is an interesting mineral that is often mistaken as either a rock or a crystal. However, labradorite is actually neither – it is a feldspar mineral. Here is an explanation of what exactly labradorite is and why it is neither a rock nor a crystal.

Labradorite is composed of calcium, sodium, and aluminum silicate minerals with a chemical formula of (Ca,Na)(Al,Si)4O8. The chemical composition and crystal structure qualify labradorite as a feldspar mineral. Feldspars are the most abundant group of minerals found in the Earth’s crust, making up around 60% of terrestrial rocks.

The term “labradorite” refers specifically to the feldspar mineral that exhibits an optical phenomenon called labradorescence. This phenomenon causes labradorite to display iridescent flashes of peacock blue, azure blue, and gold colors when viewed from different angles. The labradorescence is caused by lamellar intergrowths inside the labradorite’s crystal structure.

So what exactly makes a crystal versus a rock? A crystal is a solid material whose atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. A rock, on the other hand, is an aggregate of one or more minerals. Rocks are made up of many crystals.

Labradorite exhibits the properties of a crystalline structure – it has a consistent chemical composition and its atoms are arranged in a regular, organized pattern. However, labradorite does not grow into singular, complete crystals with naturally formed faces or points. It is most often found intergrown with other mineral crystals in igneous and metamorphic rocks.

For this reason, labradorite is classified specifically as a rock-forming mineral rather than a true crystal. It Contributes to the composition of many different rocks like anorthosite, norite, and gabbro. While it has an internal crystalline structure, labradorite does not form full, individual crystals on its own.

The stunning flashes of color from labradorescence are what make labradorite so popular for use in jewelry and ornamental stones. The iridescent play of color results from light refracting off the interior crystal lamellae. Though not a true crystal itself, labradorite’s internal crystalline structure still produces the fascinating optical effects that make it so prized.

So in summary, labradorite is neither a rock nor a true crystal – it is a mineral with a crystalline structure that comprises parts of various rocks. Labradorite’s composition and properties qualify it as a feldspar mineral. It displays the optic phenomenon of labradorescence due to its unique internal crystalline lamellae. Though not a complete crystal, labradorite’s crystalline nature gives it a special place amongst popular ornamental minerals.