Where is Tourmalinated Quartz found?
SiO2 (Quartz) with (Na,Ca)(Mg,Fe)3Al6(BO3)3Si6O18(OH)4 (Tourmaline)
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Open the appTourmalinated Quartz occurs in specific geological environments. Knowing where to look, and in what kind of rock, is the difference between going home empty-handed and finding a great specimen.
Where to find Tourmalinated Quartz
Brazil
Minas Gerais is a significant source, known for high-quality specimens with clear quartz and well-formed black tourmaline needles.
Madagascar
Produces specimens with various tourmaline colors, including black, green, and pink, within quartz.
United States
Localities in Maine, California, and North Carolina yield tourmalinated quartz, often from pegmatite deposits.
Pakistan
Known for specimens with clear quartz and distinct black tourmaline inclusions.
Afghanistan
Similar to Pakistan, producing fine examples of tourmalinated quartz.
Collecting tips
- Geological Context. Look for tourmalinated quartz in areas known for pegmatites, granitic intrusions, and hydrothermal alteration zones. Stream beds and alluvial deposits downstream from such areas can also yield specimens.
- Visual Identification. Identify clear to milky quartz with distinct, often black, needle-like or columnar inclusions. The contrast between the host quartz and the tourmaline is usually quite evident.
- Hardness Test. Quartz (Mohs 7) is harder than most common rock-forming minerals, and tourmaline (Mohs 7-7.5) is similar. This can help distinguish it from softer minerals with similar appearances.
- Crystal Habit. Observe the characteristic prismatic habit of tourmaline inclusions, often with striations, embedded within the quartz.
Quick Check
- Color:
- Clear to smoky quartz with black (or other colored) needle-like inclusions.
- Luster:
- Vitreous.
- Streak:
- White (for quartz); colorless (for tourmaline, though often not practical to streak inclusions).
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