Dumortierite Quartz is a popular lapidary material characterized by dense inclusions of fibrous blue dumortierite needles trapped within a clear or milky quartz host. It is easily identified by its distinctive denim-blue color and typical massive habit, making it a favorite for carving and jewelry.
Is this dumortierite quartz?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch dumortierite quartz with a known reference. Dumortierite Quartz sits at Mohs 7, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Dumortierite Quartz leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Dumortierite Quartz typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: blue, violet-blue, deep blue.
- 5Look at form & habitCrystal system: trigonal. Typical habit: massive.
Often confused with
Dumortierite Quartz vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Dumortierite Quartz is noticeably harder (Mohs 7 vs. 5.5-6).
How to tell apart: Dumortierite Quartz is noticeably harder (Mohs 7 vs. 5-5.5); streak differs, so Dumortierite Quartz leaves white, Lazurite leaves light blue.
How to tell apart: Luster reads vitreous on Dumortierite Quartz and waxy on Blue Chalcedony.
Often found alongside dumortierite quartz
Minerals reported to co-occur with dumortierite quartz. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SiO₂
- Mohs hardness
- 7
- Density
- 2.65 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Common
- Uses
- Lapidary, Collector, Decorative
- Host rock
- Hydrothermal Veins and Pegmatites
- Typical price
- $5-50 for cabochons or rough specimens
Where rockhounds find dumortierite quartz
Classic worldwide localities
- Namibia
- Brazil
- Madagascar
- USA
- Peru
Field-hunting tip
Look in hydrothermal veins and pegmatites country, the host setting where dumortierite quartz typically forms. If you start seeing quartz, dumortierite, muscovite in float, you are in the right ground. Field specimens usually show a massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find dumortierite quartz on the map
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