Prehnite

What is prehnite?

Prehnite has chemical formula Ca₂Al₂Si₃O₁₀(OH)₂. Mohs hardness: 6–6.5. Density: approximately 2.80–2.95 g/cm³. Refractive index: 1.61–1.64.

What gives it its color?

Iron produces the characteristic pale green to yellow-green color. Often has a translucent, milky appearance.

Where does it come from?

Major sources include South Africa, Australia, China, USA.

Treatments and how to spot them

Generally untreated. Named after Dutch colonel Hendrik von Prehn. Often forms botryoidal (grape-like) crystal clusters.

Important: Visual clues such as inclusions, color patterns, or surface features can provide preliminary observations, but they cannot replace refractive index, specific gravity, microscopic examination, and laboratory testing for a definitive identification. Treat visual clues as starting points, not final answers.

Jewelry and care tips

With hardness 6–6.5, prehnite can be used in various jewelry types. Clean with warm soapy water and a soft cloth. Avoid ultrasonic cleaners unless the stone is known to be fracture-free. Store separately from harder gemstones.

Note: Prolonged strong light or high heat may cause some color-sensitive or treated stones to fade. Brief daily wear does not usually cause immediate fading, but avoid leaving jewelry in direct sun for extended periods.

Cultural beliefs and symbolism

Prehnite carries cultural meaning across many traditions — these are folkloric and cultural traditions, not scientifically verified properties. Its associations vary by culture, and its use in astrology, chakra, or feng shui contexts should be understood as cultural expression rather than factual claims.

What affects its value?

Price is determined by color saturation, clarity, cut quality, and size. Terms like commercial color names are market descriptions — they cannot by themselves prove origin or value. Before buying: ask the seller to confirm the material identity, treatment status, dimensions, and return policy in writing.