Indigolite (blue tourmaline): properties, symbolism and care

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Indigolite, or indicolite, is blue tourmaline: a variety of elbaite, hard (7 to 7.5), dichroic and pyroelectric. It is rarer than pink and green tourmalines.

Key points

Colour	indigo blue, blue-green, pale blue to very deep blue
Mineral family	tourmaline, a variety of elbaite; boron and lithium-aluminium silicate
Crystal system	trigonal (striated prisms with a rounded triangular section)
Hardness (Mohs)	7 to 7.5
Density	about 3.0 to 3.1
Origin of the name	indigo (colour); older spelling: indicolite
Known deposits	Brazil, Namibia, Afghanistan, Nigeria, Madagascar, United States (Maine)
Special feature	strong pleochroism; pyroelectricity and piezoelectricity
Not to be confused with	Paraíba tourmaline (blue-green coloured by copper)

What is indigolite?

Indigolite (also spelled indicolite or indigolithe) is the name of blue tourmaline. It denotes a variety of elbaite, the tourmaline species with the widest range of colours, of formula Na(Li1.5Al1.5)Al6Si6O18(BO3)3(OH)3OH: a complex silicate of sodium, lithium, aluminium and boron. The blue colour, sometimes blue-green or nearly black, comes mainly from iron (and sometimes titanium). It is one of the most sought-after tourmaline colours.

It is hard (7 to 7.5), has a density of about 3.0 to 3.1, and crystallises as striated prisms in the trigonal system. Its deposits are found in pegmatites (see pegmatites): Brazil, Namibia, Afghanistan, Nigeria, Madagascar, United States (Maine). Like all tourmalines, it is sometimes found in crystals combining several colours.

The word “tourmaline” comes from the Sinhalese tōramalli, a term for coloured stones, including carnelian. Dutch merchants of the East India Company brought tourmalines from Ceylon that they called “Ceylon magnets” or “ash pullers”: when heated, they attract and then repel hot ash. This is pyroelectricity, which is also found in indigolite.

Pleochroism and cutting

Indigolite is strongly pleochroic: its colour changes depending on the direction in which it is viewed. The same crystal can look intense blue in one direction and grey-green in another (see colour and pleochroism). Lapidaries therefore orient the cut relative to the crystal axis to obtain the most pleasing colour, for example to lighten a stone that is too dark.

Be careful not to confuse it with Paraíba tourmaline, a neon blue-green coloured by copper, discovered in the late 1980s in Brazil (then in Mozambique and Nigeria) and much more expensive. Indigolite, by contrast, is a more sober stone: blue-grey, midnight blue, deep blue-green.

Traditional symbolism

Indigo blue evokes the night sky, the deep sea and calm. Modern crystal books associate indigolite with communication, intuition and serenity, and link it to the throat or third-eye chakra.

These associations are modern conventions based on colour; indigolite has no ancient tradition of its own, and no study has shown any effect of the stone on intuition or speech. A deep blue in a work room remains a calming visual anchor that many people appreciate.

Area	Correspondence cited
Chakra	throat; third eye
Element	water or air, depending on the author
Signs	Aquarius, Pisces, Libra (varies)
Keywords	communication, intuition, calm

How to use it

As jewellery: ring, pendant, earrings; the hardness of 7 to 7.5 suits regular wear, with the usual precautions (guide).
As a rough crystal: a small blue striated prism, kept as a collector's piece.
In meditation: look at the colour from two angles and note the difference (pleochroism); a small attention exercise (tutorial).
As a gift: for a tourmaline enthusiast.

Cleaning and cleansing

Cleaning: lukewarm water, mild soap, soft brush.
Sun and heat: the colour is generally stable, but avoid intense heat sources and thermal shocks, which can split a fissured stone.
Dust: tourmaline is pyroelectric: it can attract dust when heated or rubbed. A gentle wipe is enough.
Ultrasonic cleaners: not recommended if the stone is fractured or heavily included.
Symbolic cleansing: smoke, sound, moonlight (guide).

Recognising a genuine indigolite

Sign	Natural indigolite	Imitation or confusion
Colour	deep blue to blue-green, which varies with the angle	uniform electric blue: glass or treated blue topaz
Rough crystal	prism striated lengthwise, rounded triangular section	smooth cylinder: glass or resin
Interior	fractures, liquid inclusions	round bubbles: glass
Weight	density of 3.0 to 3.1	light: plastic; topaz (3.5) slightly heavier

Blue rough crystals sold at low prices may be very dark black tourmaline (schorl), kyanite or iolite. An indigolite of fine colour and gem quality is expensive and is bought with a certificate. See real or fake stone and our commitments.

How to choose

Colour remains the first criterion: a pure, saturated blue, without too much grey or black. Rough crystals are affordable; cut stones of fine colour and eye-clean quality are considerably more expensive. On a modest budget, small rough crystals or fragments are enough for a collection.

Pairings: with bicolour tourmaline, green tourmaline or pink tourmaline, to illustrate the range of colours of elbaite. To care for all your stones, read our guide.

Frequently asked questions

What is indigolite?

The blue variety of elbaite, a species of tourmaline. The spelling indicolite is also used.

Is indigolite the same as Paraíba tourmaline?

No. Paraíba is a neon blue-green coloured by copper, much rarer and more expensive. Indigolite owes its colour mainly to iron.

Why does tourmaline attract dust?

Because it is pyroelectric: when heated or rubbed, it becomes electrically charged and attracts small particles. Dutch merchants called it “ash puller”.

Is indigolite hard?

7 to 7.5 on the Mohs scale: it suits jewellery worn regularly, with care against knocks.

Why does the colour change with the angle?

Because of pleochroism: the stone absorbs light differently depending on the crystal direction. Lapidaries orient the cut relative to the crystal axis to obtain the finest colour.