Turquoise is an opaque, blue-to-green mineral and historic gemstone made of hydrated copper and aluminum phosphate. Prized for thousands of years by ancient civilizations like the Egyptians and Native Americans, it is famous for its distinct robin's egg blue or greenish hues and unique dark vein patterns.

Cornerstone gemstone profile

Turquoise

An opaque blue-to-green phosphate mineral

Species
Turquoise
Formula
Pending verification
Mohs
5–6[1]
Refractive index
Pending verification

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01

Definition

What is Turquoise?

Turquoise is an opaque blue-to-green phosphate mineral used as a gem and ornamental material. Detailed reference values are pending editorial review.

02

At a glance

Gemological properties

Measured values and species-level properties are linked to their evidence. “Pending” means the value has not cleared review.

1public references
Scientific and gemological properties of Turquoise
GemstoneTurquoiseMineral speciesTurquoise
Mineral groupPhosphatesFamilyPending verification
Chemical formulaPending verificationCrystal systemPending verification
Mohs hardnessMohs hardnessA comparative scale of scratch resistance from 1 to 10; it does not measure toughness.Learn more5–6[1]Specific gravitySpecific gravityThe ratio of a material’s density to the density of water under defined conditions.Learn morePending verification
Refractive indexRefractive indexA measurement describing how light changes speed and direction as it enters a material.Learn morePending verificationBirefringenceBirefringenceThe numerical difference between a doubly refractive material’s principal refractive indices.Learn morePending verification
Optic characterPending verificationDispersionDispersionThe separation of white light into spectral colors because refractive index varies with wavelength.Learn morePending verification
Primary colorBluePleochroismPleochroismDifferent body colors seen in some anisotropic gems when viewed along different crystallographic directions.Learn morePending verification
LusterLusterThe character of light reflected from a material’s surface.Learn morePending verificationTransparencyPending verification
CleavageCleavageA mineral’s tendency to split along specific crystallographic planes.Learn morePending verificationFracturePending verification
TenacityTenacityA material’s response to bending, breaking, crushing, or tearing.Learn morePending verificationFluorescencePending verification
StreakPending verificationAvailabilityNatural · Laboratory-grown
Jewelry suitabilityPending verification

Scope note: some physical properties describe corundum as a mineral species; ruby-specific claims are identified separately in the citations.

REF

Evidence

References & further reading

Citation numbers are deduplicated across properties, claims, sections, structured modules, treatments, inclusions, FAQs, and related educational records.

  1. [1]
    Turquoise Description.

    Gemological Institute of America

    View source
Written byThe Gem Index Editorial Team
Reviewed byReview pending
Last reviewedPending
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