Gem library
Amazonite
The water-green feldspar
Amazonite is the green variety of microcline, a potassium feldspar. Its colour, long attributed to copper, in fact comes from traces of lead combined with structural water — a fairly recent finding in mineralogy.
- Hardness (Mohs)
- 6 – 6.5
- Density
- 2.55 – 2.63
- Crystal system
- Triclinic
- Refractive index
- 1.522 – 1.530
- Cleavage
- Perfect on {001} and {010}
Mineralogical identity
- Family
- Feldspars — microcline
- Species
- Microcline
- Variety
- Amazonite
- Chemical formula
- KAlSi₃O₈ + traces of lead
- Crystal system
- Triclinic
- Classification
- Semi-precious stone
- Rarity
- Common
- Indicative price
- €0.30 – 5/ct
Etymology
From the Amazon river, where it was wrongly believed to have been discovered; the green stones attributed to Amazonia were in fact jadeite.
Physical & optical properties
- Hardness (Mohs)
- 6 – 6.5
- Density
- 2.55 – 2.63
- Refractive index
- 1.522 – 1.530
- Birefringence
- 0.008
- Cleavage
- Perfect on {001} and {010} — two directions at 90°
- Fracture
- Splintery
- Lustre
- Vitreous to pearly on cleavages
- Diaphaneity
- Translucent to opaque
- UV fluorescence
- None
- Pleochroism
- None
- Colours
- water green, pale turquoise, blue-green
Formation, geology & history
A feldspar coloured by lead
Microcline is one of the commonest feldspars in granites and pegmatites, usually white, cream or salmon pink. Its green variety, amazonite, owes its tint to traces of lead (a few thousand ppm) combined with water in the structure: heated, it loses its colour, which is how the mechanism was established. It is recognised by its often finely gridded appearance, due to the polysynthetic twinning typical of microcline, and by white albite veins that draw marbling. The crystals of Pikes Peak, Colorado, associated with smoky quartz prisms, are among the most spectacular in the mineral world.
The cleavage trap
With two directions of perfect cleavage at right angles, amazonite is markedly more fragile than its hardness of 6 suggests. A moderate knock is enough to pop off a flat, shiny flake. That calls for care in jewellery: favour thick cabochons, round beads and protective settings, and avoid rings worn daily. Experienced lapidaries orient the piece so the cleavage planes are not parallel to the surface, which limits chipping during polishing.
Market and confusions
Amazonite is affordable and plentiful as beads, cabochons, pebbles and turned objects. Its water green is often confused with turquoise, chrysoprase or jade, from which it is distinguished by white albite veins and a pearly lustre on cleavage planes. Some commercial amazonite is lightly heated or waxed to even out the tone; electric turquoise versions are dyed. Quality is judged by the intensity of the green and the fineness of the veining.
How to recognise it
- Pearly lustre on cleavage planesTilt the stone: small flat, shiny facets appear, reflecting light like mirrors. No other translucent green stone does this.
- White albite veinsMilky white marbling, often in networks or flames, is characteristic of feldspar.
- Hardness 6It just scratches glass and is marked by a file. Harder than turquoise, softer than jade.
Imitations, treatments & confusions
- Dyed howlite or magnesiteMuch softer (3.5), with black rather than white veins and a dye that bleeds with acetone.
- Sold as turquoise or jadeAmazonite has pearly cleavage planes that neither turquoise (matt) nor jade (fibrous grain) possesses.
- Water-green glassBubbles, seams, immediate warmth, no natural veining at all.
Deposits & origins
Russia (Urals and Kola — the finest, intense green), United States (Colorado, Pikes Peak: crystals associated with smoky quartz), Brazil, Madagascar, India, Namibia, Ethiopia
Care & precautions
- Brief rinsing in warm soapy water, gentle drying. No prolonged soaking.
- Intense sun fades the green: keep it out of direct light.
- Mind impacts: the double cleavage at 90° makes the stone brittle. Store individually.
- No ultrasonic cleaning or steam, which can open the cleavage planes.
Traditions & crystal healing
- Chakras
- Heart · throat
- Zodiac signs
- Virgo · Libra
- Element
- Water · Air
Tradition makes it the stone of untroubled communication: it is said to help say things without friction, set limits with a smile and recover spontaneity. Its water green links it to the heart and the throat, a pairing crystal healing associates with speaking from the heart.
The virtues described here belong to tradition and cultural heritage. They are in no way medical advice and never replace a consultation.
Frequently asked questions
Amazonite or turquoise?
Amazonite shows pearly, shiny cleavage planes, white veins and a cleaner green. Turquoise is matt, porous, with a brown or black matrix.
Why is my amazonite chipping?
Because of its perfect double cleavage at 90°. Even at hardness 6, a knock is enough to pop off a flat flake. Avoid rings worn daily.
Does it lose its colour?
Yes, under prolonged sun or heating: the colour depends on a fragile balance between lead and structural water. Keep it in the shade.