Rose quartz is a variety of the common mineral quartz, chemically defined as silicon dioxide (\(\text{SiO}_2\)). It is a macrocrystalline form of quartz, registering a 7 on the Mohs scale of mineral hardness. This durability makes it a preferred material for polished jewelry, gemstones, and decorative carvings. The stone is valued for its characteristic soft coloration and is often found in pegmatites, which are igneous rocks.
The Signature Pink Hue
The color of rose quartz ranges from a very pale pink to a deep, rosy red. This delicate coloration in the most common form, massive rose quartz, is generally caused by microscopic inclusions of fibrous minerals within the quartz structure. These nanofibrous inclusions are often related to dumortierite, a pink borosilicate mineral.
These minute fibers are highly reflective and scatter light, producing the soft pink tone. A much rarer form, sometimes called crystalline pink quartz, derives its color from trace amounts of aluminum and phosphorus that create color centers within the crystal lattice.
The two types differ in color stability when exposed to light. The massive variety is generally color-stable, but the rare crystalline pink quartz is photosensitive and can fade with prolonged exposure to strong sunlight. Exposure to high heat can cause the color in massive rose quartz to be lost.
Clarity and Internal Characteristics
Rose quartz is typically translucent, meaning light passes through it diffusely, but it is rarely transparent. The stone often exhibits a characteristic milky, cloudy, or hazy appearance, which is a direct consequence of the microscopic inclusions that cause its pink color. These minute internal fibers scatter light, giving the material its signature soft, cloudy look.
The stone’s surface luster is described as vitreous, or glass-like, though massive pieces sometimes display a waxy or greasy sheen. In some high-quality rose quartz that contains a dense concentration of these well-oriented fibrous inclusions, a phenomenon known as asterism can be observed. When cut into a cabochon or a sphere, the stone can display a six-rayed star of light shimmering across its surface. This star effect is caused by the reflection of light off the parallel-aligned internal fibers.
Natural Growth and Physical Structure
Rose quartz found and used commercially is known as massive rose quartz, which occurs in large, non-crystal-forming masses. This massive habit is found within the cores of pegmatites, which are large-grained igneous rocks. In this form, the material is anhedral, lacking well-formed external crystal faces.
The extremely rare variety, crystalline pink quartz, forms distinct, terminated hexagonal crystals, often found in clusters. Regardless of the form, the mineral does not exhibit cleavage. Instead, when broken, rose quartz fractures, producing a curved, shell-like surface known as a conchoidal fracture. The rough, unpolished material is typically irregular in shape due to its massive growth habit.