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Tourmaline facts for kids

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Tourmaline
A stone cut open and polished, revealing a bright rainbow of colors
General
Category Cyclosilicate
Formula
(repeating unit)
(Ca,K,Na, ▢)(Al,Fe,Li,Mg,Mn)3(Al,Cr, Fe,V)6
(BO3)3(Si,Al,B)6O18(OH,F)4
Identification
Color Most commonly black, but can range from colorless to brown, red, orange, yellow, green, blue, violet, pink, or hues in between; can be bi-colored, or even tri-colored; rarely can be neon green or electric blue
Crystal habit Parallel and elongated. Acicular prisms, sometimes radiating. Massive. Scattered grains (in granite).
Crystal system Trigonal
Tenacity Brittle
Streak White
Diaphaneity Translucent to opaque
Specific gravity 3.06 (+.20 -.06)
Density 2.82–3.32
Pleochroism
  • Typically moderate to strong
  • Red: definite; dark red, light red
  • Green: strong; dark green, yellow-green
  • Brown: definite; dark brown, light brown
  • Blue: strong; dark blue, light blue
Dispersion .
Ultraviolet fluorescence pink stones—inert to very weak red to violet in long and short wave
Absorption spectra Strong narrow band at 498 nm, and almost complete absorption of red down to 640 nm in blue and green stones; red and pink stones show lines at 458 and 451 nm as well as a broad band in the green spectrum

Tourmaline (pronunciation: /ˈtʊərməlɪn/, -/n/ TOOR-mə-lin, -leen) is a crystalline boron silicate mineral compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. Tourmaline is classified as a semi-precious stone. This gemstone can be found in a wide variety of colors. Depending on how much iron they contain some can be quite magnetic.

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