Mustard Tourmaline

Mustard tourmaline is a trade name for warm mustard-yellow to brownish-yellow tourmaline, a muted, earthy color between bright yellow tourmaline and brown dravite. Its tone resembles the color of mustard, giving it the name.

Depending on the specimen, the color can come from iron and titanium in magnesium-rich dravite or from manganese in elbaite, sometimes with a touch of brown. These tourmalines appeal to collectors and to jewelry designers seeking warm, autumnal earth tones.

Like all tourmalines, mustard stones show pleochroism and the group's characteristic striated prismatic crystals.

Mustard tourmaline forms in two main settings depending on its chemistry. Magnesium-rich (dravite-type) yellow-brown tourmaline forms in metamorphic and metasomatic rocks rich in magnesium and boron, while manganese-bearing yellow elbaite forms in lithium-rich granitic pegmatites.

Iron and titanium produce the brownish, ochre tones, while manganese tends toward purer yellow; intermediate mixes give the mustard color. Sources include Tanzania and Kenya (brown-yellow dravite) and Brazil, Madagascar, Nigeria, and Zambia (yellow elbaite).

Heat treatment is sometimes used to modify yellow and brown tourmaline color.

Mustard tourmaline shows mustard to brownish-yellow color, vitreous luster, hardness 7-7.5, pleochroism, striated prismatic habit, triangular cross-section, no cleavage, and doubling of back facets from high birefringence.

Pleochroism and birefringence separate it from singly refractive look-alikes. Distinguishing dravite-type from elbaite-type mustard tourmaline requires chemical analysis.

Look-alikes include yellow-brown citrine, heliodor (yellow beryl), yellow sapphire, and andalusite; tourmaline's strong birefringence, pleochroism, and habit distinguish it, while beryl and citrine show weaker doubling and different optics.

Mustard tourmaline is faceted for rings, pendants, and earrings by designers wanting warm, earthy yellow-brown gems; it is relatively affordable and pairs well with autumnal and vintage-style jewelry. Clean, evenly colored stones are most desirable.

It is also collected as crystals and specimens. Metaphysically, yellow and golden tourmalines are associated with the solar plexus chakra, confidence, willpower, and abundance, traditional associations that are not scientifically established.