Serpentine

Serpentine

Serpentine • mineral group (antigorite • lizardite • chrysotile) Formula: ~Mg₃Si₂O₅(OH)₄ with Fe/Ni substitutions • Polytypes: monoclinic & trigonal Hardness: ~2.5–5.5 • SG: ~2.55–2.65 • Luster: waxy to silky Look: apple‑to‑olive greens, mottled “snakeskin,” sometimes translucent (bowenite)

Serpentine — Greens From the Deep Earth

Serpentine is not one mineral but a trio of close cousins. Together they turn dark, magnesium‑rich rocks into soft greens and silky sheens. Some pieces carve like butter; others—like bowenite—polish to a luminous, jade‑like glow. The name comes from the stone’s serpent‑skin patterns, not because any snakes were consulted. (They would’ve asked for royalties.)

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What it is
A phyllosilicate group formed by hydration of ultramafic rocks: antigorite (platy), lizardite (fine platy), chrysotile (fibrous)
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Why it’s beloved
Soft to carve, takes a waxy to glassy polish; classic greens, veining, and “snakeskin” mottling
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Care snapshot
Moderately soft; avoid harsh acids/heat; wet‑work when cutting; protect polished surfaces

Identity & Naming 🔎

Mineral group vs. rock

Serpentine is a mineral group (antigorite, lizardite, chrysotile). A rock made mostly of serpentine minerals is called serpentinite. You’ll see both names in the wild—one is the ingredients, the other is the cake.

Gemmy varieties

Bowenite (a translucent, tough antigorite) is prized for carving and cabbing; williamsite is an apple‑green serpentine dotted with magnetite/chromite. Trade terms like “new jade,” “Afghan jade,” or “Xiuyan jade” often refer to serpentine—lovely material, just not true jade.

About fibers: Chrysotile is the fibrous serpentine (the industrial asbestos type). Lapidary and décor pieces are typically antigorite or lizardite; when working unknown rough, wet‑cut and keep dust down—good shop practice anyway.

Where It Forms 🧭

From mantle rocks + water

Serpentine forms when ultramafic rocks (peridotite, dunite) are hydrated at low to moderate temperatures. Water sneaks into olivine/pyroxene and rewrites them into serpentine + magnetite ± brucite—sometimes releasing hydrogen in the process.

Ophiolites & subduction zones

Classic places: ancient seafloor slices thrust onto land (ophiolites) and plate boundaries where fluids circulate. Veins, shear zones, and mesh textures tell the story of fluid + rock + time.

Textures by growth

Lizardite makes fine platy masses, antigorite forms undulating plates/blades, and chrysotile fills tiny veins as silky fibers. All can mix within one stone.

Recipe: hot ultramafic rock meets cool water → the earth exhales green.

Colors & Pattern Vocabulary 🎨

Palette

  • Apple to pistachio — common in fine‑grained lizardite.
  • Olive/forest — antigorite plates and veined serpentinite.
  • Black veining — magnetite/chromite seams.
  • White streaks — calcite/dolomite veins and healing lines.
  • Translucent green — bowenite cabbing rough.

Polished surfaces show waxy to oily luster; some antigorite reveals a subtle silky shimmer along plates.

Pattern words

  • Snakeskin/mottle — interlocking greens with fine mesh texture.
  • Ribbon antigorite — gently curved blades creating linear flow.
  • Verd antique — brecciated serpentine fragments cemented by calcite (a classic architectural stone).
  • Slickenside sheen — satiny, striated surfaces along ancient faults.

Photo tip: A low, raking light (~25–30°) wakes up the waxy sheen and makes magnetite veining pop. Neutral grey backgrounds keep greens true.

Physical & Optical Properties 🧪

Property Typical Range / Note
Chemistry ~Mg₃Si₂O₅(OH)₄ (Fe, Ni can substitute)
Polytypes Antigorite (platy, monoclinic); Lizardite (fine platy, trigonal); Chrysotile (fibrous, monoclinic)
Hardness (Mohs) ~2.5–3.5 typical; bowenite to ~5–5.5 (tougher, gemmier)
Specific gravity ~2.55–2.65 (feels lighter than jade)
Cleavage / Fracture Poor; parting along plates/fibers; conchoidal to splintery fracture
Luster Waxy, greasy, to silky; vitreous on polished antigorite
Transparency Opaque to translucent (bowenite, williamsite)
Optics RI ~1.54–1.57 (variable); biaxial; generally inert to weak UV
Other May be weakly magnetic from magnetite specks; calcite veins fizz in acid though serpentine itself does not
Feel test: Serpentine often feels cool and slightly soapy. If a copper coin scratches it easily, it’s likely the softer end of the group; bowenite stands up much better.

Under the Loupe 🔬

Mesh textures

Serpentinized peridotite can show a polygonal “mesh”—tiny networks where olivine grains altered from the edges inward. Magnetite dusts the seams like dark grout.

Antigorite plates

Look for undulating plates/blades that give a silky directionality. These can cause slight anisotropic polish—part of the charm.

Veins & travelers

White calcite/dolomite veins crosscut; black chromite/magnetite specks travel along fractures. A tiny magnet may barely tug on magnetite‑rich spots.

Look‑Alikes & Misnomers 🕵️

Nephrite & jadeite (true jade)

Harder & tougher (nephrite ~6–6.5; jadeite ~6.5–7); higher SG (nephrite ~2.9–3.1; jadeite ~3.3+); brighter, glassier polish. Serpentine is warmer/waxy and scratches more readily.

Prehnite & chalcedony

Both can be pale green & translucent, but they show conchoidal fracture and higher hardness (won’t scratch with a knife). Serpentine’s luster is waxy rather than glassy.

Soapstone (talc‑rich)

Softer (fingernail can mark), powdery feel, often grey; used for countertops/steatite carvings. Serpentine is firmer and usually greener.

“New jade” & dyed stones

Many bright apple‑greens are serpentine sold as “jade.” Dyes may pool in pores and along fractures. Natural serpentine shows subtle tonal shifts, not neon uniformity.

Green marble

Calcite‑rich stones marketed as “green marble” can be serpentine breccias (verd antique). Calcite veins fizz; serpentine matrix does not.

Quick checklist

  • Waxy/oily luster and cool “soapy” feel?
  • Knife can mark softer varieties; bowenite resists.
  • Heft lower than jade; possible weak magnetism from specks.

Localities & Varieties 📍

Ophiolite greens worldwide

Serpentinite belts ring the globe: Italy & Greece (classic decorative stones), Cornwall, UK (Lizard serpentine for Victorian objets d’art), California & Vermont, USA, Quebec, Canada, and many more.

Named gems

Bowenite (New Zealand “tangiwai,” Rhode Island, Taiwan) — translucent antigorite used like jade. Williamsite (Pennsylvania) — bright apple‑green with magnetite sparkles. Xiuyan (Liaoning, China) — a well‑known carving serpentine.

Labeling tip: “Serpentine (antigorite/lizardite), locality, variety (e.g., bowenite).” It keeps both science and story on the tag.

Care & Lapidary Notes 🧼💎

Everyday care

  • Clean with lukewarm water + mild soap; dry promptly.
  • Avoid harsh acids and prolonged heat; some pieces can darken or etch.
  • Store separately; quartz dust will scuff the waxy polish over time.

Jewelry guidance

  • Great for pendants, earrings, beads. For rings/bracelets, use protective bezels and mindful wear.
  • Bowenite handles daily life better than softer serpentines.

On the wheel

  • Wet‑work with light pressure. Fresh belts; keep it cool.
  • Pre‑polish 600→1200→3k; finish with chromium oxide or cerium/tin oxide on soft leather/felt for a lush sheen.
  • Slight micro‑bevels reduce edge bruising; stabilize crumbly areas sparingly if needed.
Display idea: Pair a translucent bowenite cab with a matte serpentinite slab. Same family, two moods: glow and earth.

Hands‑On Demos 🔍

Magnet speck test

Hover a tiny magnet: a whisper of pull hints at magnetite flecks along old fracture lines—common in serpentinite.

Polish personality

Tilt a polished surface under low light. Waxy serpentines glow softly; antigorite plates add a silky sweep that seems to move with you.

Small joke: serpentine—proof that a good spa day (water + rock) can change your life.

Questions ❓

Is serpentine the same as jade?
No. Serpentine can look jade‑like (especially bowenite) but it’s softer and lighter. Beautiful in its own right.

What’s bowenite?
A tough, translucent variety of antigorite prized for carving and jewelry. It takes a glassier polish than softer serpentines.

Does all serpentine contain asbestos?
No. Only the chrysotile polymorph is fibrous. Most gem/décor material is antigorite or lizardite. When cutting unknown rough, wet‑work and use dust control as good workshop habit.

Why does my piece fizz in spots?
The serpentine won’t, but calcite veins will. It’s a common and pretty companion feature.

Can it take a high polish?
Yes—especially bowenite. Use fine pre‑polish and chromium/cerium oxides. Expect a waxy‑to‑vitreous glow rather than diamond‑like sparkle.

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