Quartz with a memory of fibers

Tiger eye begins as crocidolite (blue fibrous amphibole). Over time, silica replaces the fibers—pseudomorphing them with microcrystalline quartz—yet keeps their parallel alignment. That preserved “silk” scatters light as a bright line: chatoyancy.

Why red?

Iron in and around the former fibers oxidizes. Goethite → hematite shifts the palette from golden browns toward red and mahogany. Many red pieces on the market are kiln‑warmed to nudge this reaction along; the structure remains quartz throughout.

Palette

• Deep mahogany — hematite‑rich zones with strong “eye.”
• Brick red — classic warmed tone.
• Russet/cinnamon — transitional areas toward golden bands.
• Honey/amber — remnant golden tiger‑eye streaks.
• Ink lines — fine iron‑oxide partings emphasizing contrast.

Stones often show layered ribbons where red and golden bands alternate—gorgeous in wide cabs and beads.

Pattern words

• Cat’s‑eye band — the bright line that glides under light.
• Ribboned chatoyancy — multiple parallel bands for a wider “glow.”
• Hematoid blush — diffuse red wash where hematite is fine‑grained.
• Tiger‑iron interlayers — if alternating with red jasper/hematite (see cousins).

Photo tip: One small light at ~30° makes the eye move. Keep the light still and tilt the stone—the band will chase you like a curious cat.

Silk, not cracks

At 10×, you’ll see fine, parallel fibers or bands—straight and coherent. True cracks wander or branch; fiber bands keep their lane.

Hematite clues

Redder zones show minute, opaque specks/films along the banding. Under strong light they read as a velvety haze rather than glitter.

Orientation test

Rotate the cab: the cat’s‑eye line should swing smoothly. If it breaks or stops, the cut intersected the bands at an angle.

Red jasper

Similar color but no chatoyancy. Jasper shows granular/cherty texture; the “eye” effect is absent.

Tiger iron

A natural composite: tiger eye + hematite + red jasper in bold, metallic stripes. Heavier, with steel‑grey bands that reflect like metal.

Pietersite

Brecciated and re‑cemented tiger/ hawk’s eye → swirling chatoyancy instead of straight ribbons. Looks like a stormy sky in motion.

Fiber‑optic glass (“cat’s eye”)

Uniform, neon colors with an extremely sharp, perfectly centered eye that barely changes with tilt; softer and lacks natural banding.

Dyed agate

Can be red and shiny but won’t show a moving cat’s‑eye band. Bands follow agate patterns, not straight silks.

Quick checklist

• Does a single bright band glide under light?
• Do fine parallel fibers appear at 10×?
• Color natural (rust/mahogany) vs. uniform neon (often dyed)?

Classic sources

Northern Cape, South Africa is the historic heartland for tiger‑eye deposits; red material commonly comes from the same belts. Additional production occurs in Namibia and Western Australia (where tiger iron also occurs).

Elsewhere

Quartz with tiger‑eye texture is also worked in Brazil, India, and other localities. The red hue may be natural or heat‑brought depending on the lot.

Everyday care

• Quartz‑hard, but protect from sharp impacts (edges can chip).
• Clean with lukewarm water + mild soap + soft cloth; rinse & dry.
• Avoid prolonged high heat; extreme heat can mute color or stress the stone.

Jewelry use

• Great for cabs, beads, and inlay. For rings/bracelets, consider protective bezels.
• If set with adhesives, skip hot ultrasonics/steam to preserve the mount.

Lapidary

• Orient slabs so fibers run parallel to the long axis of the cab—strongest eye.
• Work cool; pre‑polish thoroughly (to 3k–8k) before final cerium/oxide.
• Chamfer edges slightly to protect the silk where it meets the surface.

Chase the eye

Point a small flashlight at the cab and slowly tilt. The bright cat’s‑eye band should slide across the dome like a spotlight following a performer.

Fiber finder

Under a 10× loupe, look for straight, parallel silks. If the “lines” wander like rivers, you may have pietersite’s brecciated swirl instead.