Gem library
Unakite
The pink and green granite of the Appalachians
Unakite is neither a mineral nor a gem: it is a granite whose dark minerals have been replaced by pistachio-green epidote, leaving salmon-pink feldspar and quartz. That pink-and-green contrast has made it a popular ornamental stone.
- Hardness (Mohs)
- 6 – 7
- Density
- 2.85 – 3.20
- Crystal system
- Polycrystalline rock
- Refractive index
- 1.55 – 1.78 (variable)
- Cleavage
- None (rock)
Mineralogical identity
- Family
- Altered igneous rock (epidotised granite)
- Species
- Assemblage: epidote + feldspar + quartz
- Variety
- Unakite
- Chemical formula
- Assemblage — epidote Ca₂Al₂(Fe³⁺,Al)(SiO₄)(Si₂O₇)O(OH)
- Crystal system
- Polycrystalline rock
- Classification
- Ornamental rock
- Rarity
- Very common
- Indicative price
- €0.10 – 1/ct
Etymology
From the Unaka Mountains, on the Tennessee–North Carolina border, where the rock was first described.
Physical & optical properties
- Hardness (Mohs)
- 6 – 7
- Density
- 2.85 – 3.20
- Refractive index
- 1.55 – 1.78 (variable)
- Cleavage
- None (rock)
- Fracture
- Splintery
- Lustre
- Vitreous to dull
- Diaphaneity
- Opaque
- UV fluorescence
- None
- Pleochroism
- None
- Colours
- green and pink, pistachio green, salmon pink
Formation, geology & history
A transformed granite
Originally a classic granitic rock: feldspar, quartz, biotite or hornblende. A hydrothermal metamorphic episode — hot pressurised water circulation, often linked to an orogeny — replaced the ferromagnesian minerals with epidote, a calcic silicate of a very characteristic pistachio green. That process, epidotisation, leaves intact the potassium feldspar, whose iron oxidation gives the salmon pink, and the translucent grey quartz. The result is a rock mottled green and pink, whose look varies greatly with the proportions of the three components. Overall hardness, between 6 and 7, depends on which mineral is tested: quartz scratches glass, epidote slightly less.
Epidote, the key mineral
Epidote alone is a well-regarded collector's mineral, crystallising as striated olive to black-green prisms, notably in the Austrian Alps (Knappenwand) and Pakistan. Its highly saturated pistachio green is immediately recognisable and occurs in many metamorphic settings — geologists use it as a marker of temperature and pressure conditions. In unakite it is present as millimetre grains and clusters, giving the green mottling. A neighbouring rock, «Rainforest rhyolite», is sometimes sold as unakite: it is a different, browner assemblage.
Use and market
Unakite is quarried in blocks and works easily: polished pebbles, spheres, cabochons, beads, eggs and decorative objects make up most of its market, at very low prices. It has also been used as a building and decorative stone: it appears in the steps and facings of Virginia public buildings, and a block of unakite is among the commemorative stones of the Washington Monument. Its robustness — hardness 6-7, no cleavage, insensitivity to water — makes it one of the easiest ornamental stones in the trade to live with.
How to recognise it
- Mottled pink and pistachio greenThe combination of pink grains (feldspar) and pistachio green (epidote) with grey quartz is unique and cannot be confused with anything else.
- Visible rock grainIndividual crystals can be seen with the naked eye: it is a rock, not a homogeneous mineral. A smooth, even green-pink is an imitation.
- Hardness 6-7It scratches glass. A soft pink and green rock is more likely a marble or dyed serpentine.
Imitations, treatments & confusions
- Dyed rocks sold as unakiteMarble or howlite dyed pink and green lack the visible crystalline grain and are scratched by a knife.
- Reconstituted resinMottling patterns too regular and identical from bead to bead, lightness, plastic smell on a hot point.
- Confusion with rhyolite or pink graniteNot frauds but neighbouring rocks: unakite is defined by the presence of pistachio-green epidote, without which the name is abusive.
Deposits & origins
United States (Unaka Mountains, Great Smoky Mountains — type locality; Virginia, where it is the state stone), South Africa, Brazil, China, Sierra Leone, Switzerland, Zimbabwe
Care & precautions
- Warm soapy water and a soft brush: with no cleavage and no porosity, it is a very tolerant stone.
- Insensitive to sunlight: the colours come from stable minerals, not fragile pigments.
- Ultrasonic-safe on sound pieces.
- The polish can dull on the softer epidote grains; a gentle repolish revives it.
Traditions & crystal healing
- Chakras
- Heart · third eye
- Zodiac signs
- Scorpio · Libra
- Element
- Earth
Tradition presents it as a stone of balance between the heart (the green) and grounding (the pink), useful for periods of convalescence and gradual rebuilding. It is credited with working «gently», in stages, rather than producing a marked effect — hence its reputation as a stone of patience.
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
Is unakite a precious stone?
No, it is an ornamental rock: an epidotised granite. Its value is purely decorative, but its robustness and unique pink-green pattern make it a pleasant stone to work.
Why those two colours?
The pink is slightly oxidised potassium feldspar, the green is epidote that replaced the dark minerals of the original granite during a hydrothermal episode.
Can it go in water?
Yes, with no restriction: hardness 6-7, no cleavage, no notable porosity, stable minerals. It is one of the easiest stones to care for.