Dumortierite Quartz
Quartz with Dumortierite inclusions (SiO2 + Al7(BO3)(SiO4)3O3) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal (Quartz host) / Orthorhombic (Dumortierite crystals); usually seen in massive or fibrous habits within the host.
Mineral Group
Silicates; specifically a combination of Tectosilicates (Quartz) and Nesosilicates (Dumortierite).
Chemical Formula
SiO2 (Quartz base) with Al7(BO3)(SiO4)3O3 (Dumortierite inclusions), often with traces of Fe and Ti
Formation Process
Metamorphic or Hydrothermal; forms when boron-rich fluids interact with aluminum-rich minerals in metamorphic environments, often crystallizing within silica-rich veins.
About This Crystal
A tumbled, opaque to translucent stone with a deep denim-blue or violet-blue color. It features a waxy to vitreous luster and typically shows a mottled or fibrous appearance due to the inclusion of tiny dumortierite needles within the quartz matrix.
Physical Characteristics
Color: Indigo to dark blue; Streak: White; Cleavage: None (in quartz) / Poor (in dumortierite); Fracture: Conchoidal to uneven; Specific Gravity: 2.65 - 3.41; Fluorescence: Generally inert to weak blue under LWUV.
Optical Properties
Refractive Index: 1.544 - 1.686; Birefringence: 0.009 - 0.027; Pleochroism: Strong (blue, violet, or red-brown in the inclusions); Doubly refractive.
Hardness & Durability
Origin Region
Brazil (Bahia), Madagascar, South Africa, and the USA (Nevada/California). Often found in aluminum-rich metamorphic rocks and pegmatites.
Hardness & Durability
Mohs Hardness: 7 to 8.5 (Quartz is 7, Dumortierite is 7-8.5); Toughness: Good; Highly durable and suitable for all types of jewelry.
Care & Maintenance
Clean with warm soapy water and a soft brush; safe for ultrasonic cleaning if no significant fractures are present. Avoid prolonged exposure to high heat.
Rarity & Value
Uncommon; more affordable than sapphire but valued for its unique blue color. Price is dictated by the richness of the blue hue and the size of the specimen; treatments are very rare.
Special Characteristics
Known for its 'denim' look; can occasionally show chatoyancy if the fibrous inclusions are densely and parallelly packed.
Lore & History
Historically used as a decorative stone; in modern crystal belief, it is known as the 'Stone of Patience' and 'Stone of Order,' associated with the Throat and Third Eye chakras to enhance mental discipline and communication.