Dumortierite Quartz
Quartz var. Dumortierite-bearing · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal (quartz host), Orthorhombic (dumortierite inclusions). Typically appears as massive or tumbled aggregates.
Mineral Group
Silicates (Tectosilicate host with Nesosilicate inclusions)
Chemical Formula
SiO2 (Quartz) with Al7BO3(SiO4)3O3 (Dumortierite inclusions)
Formation Process
Metamorphic or Hydrothermal. Formed when aluminum-rich fluids crystallize into dumortierite needles within a growing quartz matrix or as a replacement mineral.
About This Crystal
A dense, opaque to translucent deep navy to royal blue stone. It exhibits a waxy to vitreous luster when polished. The color is typically uniform but may show darker blue specks or lighter quartz zones.
Physical Characteristics
Color: Deep blue, violet-blue; Streak: White; Cleavage: None (in quartz form); Fracture: Conchoidal to uneven; Specific Gravity: 2.65–2.90; Fluorescence: Generally inert or weak blue-white.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009; Pleochroism: Strong (in pure dumortierite crystals, less visible in massive quartz form); Optical Phenomenon: Occasional chatoyancy if fibrous.
Hardness & Durability
Origin Region
Brazil (Minas Gerais), South Africa, Madagascar, and Namibia. Occurs in regional metamorphic rocks and pegmatites.
Hardness & Durability
Mohs Hardness: 7.0 to 8.5 (Quartz is 7, pure Dumortierite is 8.5). High durability and excellent for daily jewelry wear.
Care & Maintenance
Clean with warm soapy water and a soft brush. Avoid harsh chemicals and sudden temperature shifts. Safe for ultrasonic cleaning if no significant fractures are present.
Rarity & Value
Uncommon in high-quality blue saturation. Value is based on the intensity of the blue color and polish quality. Specimens are generally affordable but the 'denim blue' variety is highly sought after.
Special Characteristics
Known for its rich 'Denim Blue' color. Microscopic fibrous inclusions of dumortierite provide the intense pigmentation that distinguishes it from sodalite or lapis lazuli.
Lore & History
Named after the French paleontologist Eugene Dumortier. Historically used as a decorative stone. In metaphysical lore, it is known as the 'Stone of Patience' and is associated with the Throat and Third Eye chakras.