Dumortierite Quartz
Quartz var. Dumortierite-bearing Quartz · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal/Hexagonal systems; typical habit as massive aggregates or acicular inclusions within quartz crystals
Mineral Group
Silicates (Tectosilicate Quartz with Nesosilicate Dumortierite)
Chemical Formula
SiO2 with AlAl6BSi3O18 inclusions
Formation Process
Hydrothermal or Metamorphic; dumortierite typically forms in aluminum-rich regional metamorphic rocks or pegmatites, later encased by quartz
About This Crystal
Vibrant blue to violet-blue massive appearance with a vitreous to waxy luster. Most commonly seen as opaque to translucent massive clusters or as fibrous blue needles within transparent quartz crystals.
Physical Characteristics
Color: Deep blue to cornflower blue; Streak: White; Cleavage: Poor; Fracture: Conchoidal to uneven; Specific Gravity: 2.65 - 3.40; Fluorescence: Generally inert to weak blue-white
Optical Properties
Refractive Index: 1.544 - 1.690; Birefringence: 0.009 - 0.020; Pleochroism: Strongly pleochroic when seen in pure crystal form (red, blue, violet)
Hardness & Durability
Origin Region
Brazil (Bahia), Madagascar, South Africa, and Mozambique; typically found in granitic pegmatites or metamorphic rocks
Hardness & Durability
Mohs Hardness: 7.0 - 8.5 (quartz is 7, pure dumortierite is 8.5); High toughness; Excellent durability for jewelry and carving
Care & Maintenance
Cleans well with warm soapy water; avoid harsh chemicals and ultra-high heat; generally stable in sunlight
Rarity & Value
Uncommon; value is determined by color intensity and the aesthetic of the inclusions; specimens from Brazil are highly prized
Special Characteristics
Displays distinct 'denim' blue coloring; acicular (needle-like) inclusions often form 'starburst' or 'fan' patterns within transparent quartz
Lore & History
First described in 1881 and named after paleontologist Eugène Dumortier. It is traditionally known as the 'Stone of Patience' and associated with mental clarity and organizational discipline.