What buyers notice first

• Pattern: strong banding/orbs, balanced negative space.
• Color: natural palette with pleasing contrasts.
• Finish: even, “wet‑look” polish without orange peel.

What lapidaries check

• Porosity: pits/vesicles < 1–2% of face for cabs.
• Cracks: avoid perlitic “onion‑skin” cracks on faces.
• Orientation: bands/orbs compose well at 30–60°.

Catalog shorthand (helpful)

• Type: flow‑banded • orbicular • welded tuff • obsidian pair
• Look: “ribbons” • “orbs/constellations” • “fiamme streaks”
• Use: cabbing • slab décor • teaching set • bookends

Flow‑Banded Rhyolite

• Continuity: Ribbons that travel across the face (fewer dead‑ends).
• Contrast: 2–3 hue families (cream/pink/oxide red works well).
• Undercut control: Avoid coarse saw marks; finish with fresh belts to prevent band grooving.

Orbicular / Spherulitic (“Leopardskin”)

• Orb quality: Dense, well‑rimmed orbs with minimal mushy halos.
• Spacing: A mix of sizes (1–20 mm) composes better than uniform dots.
• Pits: Check orb centers—fill can pop; grade down if widespread.

Welded Tuff / Ignimbrite

• Fiamme lines: Elegant, directional streaks; minimal crumbly pumice ghosts.
• Strength: Middle‑zone welds cut cleaner than glassy tops/bottoms.
• Teaching value: Label “fiamme/eutaxitic fabric” for educational sets.

Obsidian & Perlite (Rhyolite‑related)

• Obsidian pairs: A glass chip beside a flow‑banded slab tells a great story.
• Perlite: Clear onion‑skin cracking; label as hydrated rhyolitic glass.

Utah, USA — “Wonderstone” (banded)

Vernon Hills material: vividly banded welded vitric tuff of rhyolitic composition—classic flow patterns in warm creams, tans, and reds. Great for slabs and cabs. :contentReference[oaicite:0]{index=0}

Oregon, USA — Thunderegg country

Oregon’s official state rock is the thunderegg—agate/opal fillings in rhyolitic hosts. Major deposits span Crook, Jefferson, Malheur, Wasco & Wheeler counties. Pair cut thunderegg halves with host rhyolite for storytelling sets. :contentReference[oaicite:1]{index=1}

California, USA — Bishop Tuff (ignimbrite)

Iconic welded tuff from the Long Valley Caldera—streaky fiamme and columnar‑jointed outcrops; prized for educational slabs showing ash‑flow welding. :contentReference[oaicite:2]{index=2}

Yellowstone, USA — Obsidian Cliff

Early Quaternary Plateau Rhyolite flow famous for obsidian used in tools; superb to pair a tiny legal obsidian chip (from allowed localities) with a rhyolite explanation card—collecting is prohibited inside the National Park. :contentReference[oaicite:3]{index=3}

Chihuahua, Mexico — “Leopardskin” (orbicular)

Orbicular/spherulitic rhyolite marketed as “leopard skin jasper”; Agua Caliente area is a noted source. Look for crisp orbs and stable matrix. :contentReference[oaicite:4]{index=4}

Queensland, Australia — “Rainforest Rhyolite”

Mount Hay near Rockhampton yields spherulitic rhyolite (often with agate‑filled cavities); also famous for thundereggs. :contentReference[oaicite:5]{index=5}

Pantelleria, Italy — Peralkaline rhyolite (pantellerite)

Volcanic island dominated by peralkaline rhyolites (pantellerite→trachyte). Green Tuff ignimbrite and calderas create complex textures. :contentReference[oaicite:6]{index=6}

Iceland — Landmannalaugar Rhyolite

Multicolored rhyolite mountains (Torfajökull system), famed for pastel banding and hot‑spring landscapes—great for educational cards on rhyolite color. :contentReference[oaicite:7]{index=7}

New Zealand — Taupō Volcanic Zone

One of the world’s most productive rhyolite caldera regions—ignimbrites, domes, and ash deposits around Lake Taupō; perfect context for welded‑tuff pieces. :contentReference[oaicite:8]{index=8}

Milos, Greece — Perlite (hydrated rhyolitic glass)

Industry‑leading perlite island; perlite forms by hydration/cracking of rhyolitic glass—excellent to show alongside obsidian and rhyolite as a “one magma” trio. :contentReference[oaicite:9]{index=9}