Amethyst is a variety of quartz. Its characteristic purple color makes it one of the most recognizable minerals globally. To understand what amethyst looks like on the outside, it is important to examine its natural, raw state before it is cut or polished into a gemstone. This raw appearance is shaped by the geological processes that form the crystal, giving it a distinct visual signature.
The Signature Look Color and Zoning
The most striking feature of raw amethyst is its purple coloration, which spans from a light, rosy lavender, sometimes called “Rose de France,” to an intensely saturated, deep violet hue. This color is caused by trace amounts of iron impurities within the quartz crystal lattice. Natural gamma radiation from the surrounding host rock then interacts with these iron impurities, altering the crystal structure to produce the purple color.
A closer look at a raw specimen often reveals color zoning, where the purple color is not evenly distributed. This zoning appears as bands, patches, or triangular sectors of varying color intensity, sometimes alternating with clear or white quartz. The deepest purple is frequently concentrated near the tips of the crystals. Amethyst is typically transparent to translucent, allowing light to pass through and showcasing the depth and range of its coloration.
Crystal Habit and Growth Forms
Amethyst crystals belong to the trigonal crystal system, and their shape, or crystal habit, is highly distinctive. Individual crystals commonly form as six-sided prisms that terminate in a six-sided pyramid. These six-sided points are often the most visually appealing part of a raw specimen, catching the light with their defined faces.
In nature, amethyst rarely occurs as a single crystal but is usually found in clusters. These clusters are often “drusy” formations, where a multitude of small, tightly packed crystals grow together, creating a sparkling surface. The most famous form is the geode, which begins as a hollow cavity, often within volcanic rock. The external surface of an unopened geode is typically a rough, unassuming sphere or oval of rock, which offers no hint of the beauty within.
Surface Texture and Associated Minerals
The surface of a raw amethyst crystal typically exhibits a vitreous, or glassy, luster on its defined faces. This glassy shine can be obscured by dust, matrix rock residue, or natural roughness from its environment. The raw surfaces of crystal clusters and the base of geodes often show a more rugged, uneven texture, particularly where the specimen was attached to its host rock, known as the matrix.
Raw amethyst frequently occurs alongside other minerals that were present in the forming environment. Iron-based minerals such as goethite and hematite are common companions, sometimes appearing as reddish-brown or yellowish staining on the crystal surface or the surrounding matrix rock. The host rock itself is often a dark, fine-grained volcanic rock, providing a stark contrast to the purple crystals.