What is the Stone that Looks Like Turquoise?
Turquoise is a popular semiprecious gemstone that has been used in jewelry and decorations for thousands of years. Its striking blue-green color is very distinctive and highly valued. However, there are several other minerals that can resemble turquoise in color and appearance. These turquoise lookalikes are often referred to as “faux turquoise” or “turquoise simulants.”
Some of the most common stones that can be mistaken for turquoise include:
Chrysocolla
Chrysocolla is a hydrated copper silicate mineral that forms in crusty druzy masses in copper-bearing rock. Its color ranges from greenish blue to cyan blue, often with natural black veining similar to turquoise. Chrysocolla and turquoise are often found together in copper deposits.
Chrysocolla is softer and more porous than turquoise, rating only 2.5-4 on the Mohs hardness scale compared to turquoise’s 5-6 rating. It also lacks the waxy luster of natural turquoise. Under magnification, chrysocolla will show a botryoidal structure while turquoise has an evenly grained matrix.
Variscite
Variscite is an uncommon aluminum phosphate mineral that forms in nodules and veins near phosphate rock deposits. Its color varies from bluish green to intense green, sometimes with dark spiderweb matrix patterns.
Variscite is relatively soft at around 4 on the Mohs scale. It lacks the finely grained crystalline structure of turquoise and has a more granular appearance under magnification. Distinctive darker green and black color variations also help distinguish variscite from turquoise visually.
Magnesite
Magnesite is a magnesium carbonate mineral that naturally forms in veins as well as sedimentary deposits. Its color ranges from pale green to deep blue-green. Massive cryptocrystalline magnesite is sometimes confused with turquoise.
Magnesite has a lower hardness of 3.5-4.5 on the Mohs scale. It also has a lower specific gravity of 2.9-3.1 compared to turquoise’s 2.6-2.9 range. Under magnification, magnesite lacks the fine crystalline structure of turquoise.
Smithsonite
Smithsonite is a zinc carbonate mineral that forms botryoidal globules and stalactite-like crusts around zinc deposits. Its blue-green colors closely resemble turquoise. However, smithsonite is relatively soft with a Mohs hardness of 4.5-5. It also has a botryoidal colloform banded structure visible under magnification, unlike turquoise’s cryptocrystalline matrix.
Pectolite
Pectolite, also known as larimar when it has a blue color, is a sodium calcium silicate hydrate mineral. It forms in volcanic and pegmatite rock, often displaying attractive blue and green banded patterns.
Though visually similar, pectolite is much softer than turquoise, rating only 4-4.5 on the Mohs scale. It also has a fibrous structure and pearly luster that distinguishes it from turquoise under close inspection. Natural pectolite lacks the matrix patterns of turquoise.
Dumortierite
Dumortierite is a fibrous aluminum boro-silicate mineral that occurs in metamorphic rock. Its blue varieties can closely resemble turquoise. However, dumortierite is much harder than turquoise at 7-8.5 on the Mohs scale. It also lacks the veining and matrix patterns characteristic of turquoise. Under magnification, dumortierite shows distinctly fibrous aggregates.
Phosphosiderite
Phosphosiderite is a hydrated iron phosphate mineral that forms botryoidal and reniform crusts in granitic pegmatites. Its blue-green colors are similar to turquoise, but phosphosiderite is much softer with a Mohs hardness of only 2.5-4. It also has a vitreous luster that contrasts with turquoise’s more waxy appearance.
Apatite
Some rare gem-quality apatite can be cut into turquoise-like cabochons. Apatite is most commonly yellowish green, but also occurs in bluish green hues. However, apatite has much greater hardness of 5 on the Mohs scale. Under magnification, it also lacks the fine cryptocrystalline structure of turquoise, instead showing prismatic crystal structure.
Dyed Quartz and Magnesite
Pale green quartz or magnesite is sometimes artificially dyed to produce a turquoise color. This imitation turquoise can usually be identified by testing for dye using a warm pin, acetone, or scratch test. The softer nature of dyed quartz and magnesite compared to natural turquoise is also a distinguishing trait.
Reconstructed Turquoise
Reconstituted or “stabilized” turquoise is produced by grinding up natural turquoise fragments and bonding them with resins or plastics. The material is then hardened and cut into cabochons. Stabilization impregnates the porous turquoise, improving both color consistency and durability. Most reconstituted turquoise is detectable under magnification by a clearly composite structure and plastic-like matrix patterns.
How to Tell Real Turquoise from Imitations
There are several effective tests that can help identify real natural turquoise and distinguish it from lookalike gemstones:
– Hardness testing – Natural turquoise has a Mohs hardness of 5-6. A simple scratch test can help weed out softer stones like variscite, chrysocolla, magnesite, and smithsonite.
– Hot pin test – Many imitation stones are made of plastic compounds. A heated pin tip pressed into an inconspicuous spot will produce a strong melty plastic smell from composites.
– Specific gravity – Natural turquoise has a specific gravity around 2.60-2.90. Stones with markedly different densities are likely fakes.
– Examination under magnification – The fine grained cryptocrystalline structure of real turquoise is distinctive when viewed under 10x magnification or higher. Plastics and other materials will show very different characteristics.
– Matrix patterns – The natural veining and dendritic matrix patterns seen in turquoise are hard to duplicate convincingly. Imitation turquoise often shows clearly artificial banding and mottling.
– Color distribution – Natural turquoise generally has uneven color distribution. Uniform “too perfect” color is a giveaway sign of stabilized or reconstructed turquoise.
– Professional gemological testing – Advanced laboratory tests like refractometry, spectrometry, and chemical analysis can positively identify natural turquoise based on optical properties and composition.