The rocks most commonly substituted for genuine turquoise are Howlite and Magnesite, both of which are naturally white and porous, making them ideal for dyeing to achieve turquoise-like blue and green hues, often with a dark veining to mimic the matrix found in natural turquoise. Besides these, other natural minerals like Variscite and Chrysocolla can also bear a resemblance.
Common Turquoise Look-Alikes
Many materials, both natural and artificial, are used to imitate the distinctive blue-green color and matrix patterns of turquoise.
Howlite
Howlite is a borate mineral known for its distinctive dark grey or black veining against a white background, resembling spiderweb patterns. In its natural state, it is opaque white. Due to its porous nature, Howlite is frequently dyed blue or blue-green to closely mimic turquoise.
Magnesite
Similar to Howlite, Magnesite is a white, opaque mineral with a porous structure that readily absorbs dye. It often exhibits natural veining that, when dyed blue, can be remarkably similar in appearance to turquoise, especially when a dark dye is used to highlight the "matrix" lines.
Other Natural Minerals
- Variscite: This hydrated aluminum phosphate mineral often occurs in shades of green to bluish-green, sometimes with black or brown matrix, making it easily confused with turquoise.
- Chrysocolla: A copper cyclosilicate mineral that typically forms in vibrant blue-green colors, often found intergrown with other copper minerals and quartz. Its color can closely resemble some types of turquoise.
Dyed & Synthetic Materials
Beyond natural stones, various other materials are used:
- Dyed Jasper: Some forms of jasper can be dyed blue to mimic turquoise.
- Glass and Plastic/Resin: These artificial materials are also shaped and colored to imitate turquoise, often featuring highly uniform color and unnatural-looking matrix lines.
Distinguishing Genuine Turquoise from Imitations
Identifying genuine turquoise from its imitations often involves observing several characteristics, including color, matrix, texture, and significantly, hardness.
Hardness Comparison
One practical way to differentiate genuine turquoise from common imitations like Howlite and Magnesite is by comparing their hardness on the Mohs scale. Genuine turquoise is relatively harder than these substitutes.
Material | Mohs Hardness | Notes |
---|---|---|
Genuine Turquoise | 5-6 | A relatively soft gemstone, but harder than common dyed substitutes. |
Howlite | 3.5 | Significantly softer, easily scratched by harder materials. |
Magnesite | 3.5-4.5 | Also softer than turquoise, though slightly harder than Howlite. |
This difference in hardness means that genuine turquoise is more resistant to scratching than Howlite or Magnesite. While this test requires careful application to avoid damaging specimens, it highlights why minerals of varying hardnesses can be used to distinguish between these materials.
Other Distinguishing Features
- Color Consistency: Genuine turquoise often has slight variations in color, whereas dyed stones or synthetics might have unnaturally uniform coloring.
- Matrix: The dark veining (matrix) in genuine turquoise is naturally integrated into the stone. In imitations, especially dyed ones, the matrix might appear painted on, too uniform, or lack depth.
- Temperature: Genuine stones tend to feel cool to the touch, while plastic or resin imitations might feel warmer.
- Weight: Natural stones are generally denser and heavier than plastic or resin counterparts of the same size.