Dumortierite Quartz
Quartz with Dumortierite inclusions (SiO2 + Al7(BO3)(SiO4)3O3) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal (Quartz host) / Orthorhombic (Dumortierite inclusions); typically found in massive or fibrous habits when used in lapidary.
Mineral Group
Silicates (Tectosilicate host with Nesosilicate inclusions)
Chemical Formula
SiO2 (Quartz matrix) containing Al7(BO3)(SiO4)3O3 (Dumortierite inclusions)
Formation Process
Hydrothermal or Metamorphic; typically forms as quartz crystallizes around pre-existing fibrous blue Dumortierite crystals or through simultaneous growth.
About This Crystal
A translucent to opaque tumbled stone featuring a denim-blue to navy-blue coloration. The blue is distributed as dense, cloud-like or fibrous inclusions within a clear to milky quartz matrix, exhibiting a vitreous luster.
Physical Characteristics
Color: Denim blue to dark blue; Streak: White; Cleavage: None (Quartz has none); Fracture: Conchoidal; Specific Gravity: 2.65–2.90; Fluorescence: Generally inert, but may show weak blue/white under LWUV.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009; Pleochroism: Strongly pleochroic in pure Dumortierite (Blue/Violet/Clear), but masked when included in quartz.
Hardness & Durability
Origin Region
Madagascar, Brazil, South Africa, and the United States (California/Nevada). Often found in aluminum-rich metamorphic rocks and pegmatites.
Hardness & Durability
Mohs Hardness: 7.0 (Quartz) to 8.5 (Dumortierite inclusions). Extremely durable and suitable for all jewelry types.
Care & Maintenance
Clean with warm soapy water. Resistant to most chemicals; safe for ultrasonic cleaning unless heavily fractured. Store separately from softer stones like Calcite.
Rarity & Value
Uncommon. High-clarity specimens with vibrant blue star-like or rutilated Dumortierite are rare and highly valued by collectors. Tumbled grades are affordable.
Special Characteristics
Displays a unique 'Denim' blue color rarely found in other silicate minerals. Can occasionally show chatoyancy if the inclusions are sufficiently fibrous and aligned.
Lore & History
Historically used as a 'Stone of Patience.' In modern crystal lore, it is associated with the Throat and Third Eye chakras, believed to enhance mental discipline and organizational skills.