Obsidian, but pebble‑perfect

Obsidian is natural volcanic glass—silica‑rich melt quenched so fast that crystals never had time to form. Apache tears are simply small, rounded pieces of obsidian, typically 1–5 cm, that occur as discrete nodules in or weathered out of pale perlite (hydrated volcanic glass).

About the name

The term “Apache tear” is associated with 19th‑century frontier tales retold around the Arizona ranges. Whatever the story you hear, it’s respectful to treat the name as place‑lore tied to the U.S. Southwest rather than a scientific label. Mineralogically, they’re obsidian nodules.

Quench, then hydrate

Silica‑rich lava (rhyolite) cools rapidly, freezing into glassy obsidian. Later, groundwater hydrates and expands parts of the glass into pale, frothy perlite, leaving tougher obsidian cores as rounded nodules.

Onion‑skin cracks

Hydration produces perlitic fractures—concentric, onion‑skin cracks around nodules. Weathering exploits those cracks and frees the obsidian “tears” from the host rock.

Why they glow brown

Obsidian contains iron and other trace elements dispersed through the glass. In thin section or strong back‑light, the otherwise black glass transmits a smoky to cola‑brown light—classic Apache tear test.

Palette

• Inky black in ambient light.
• Smoky/coffee brown when backlit—sometimes with warm amber edges.
• Perlite rind as pale grey/white host rock attached to some nodules.

Surfaces can be naturally matte from weathering or glassy if freshly chipped or polished.

Pattern words

• Conchoidal fracture — curved, shell‑like chips with Hertzian cones.
• Flow lines — faint streaks/banding frozen into the glass.
• Perlitic rings — onion‑skin cracks around nodules or within the host perlite.

Photo tip: Place the stone on a phone flashlight (screen side down) or a window edge: the brown glow appears instantly, and flow lines pop.

Flow texture

At 10×, look for faint flow streaks and strain bands—wispy lines curving with the pebble. They’re subtle but satisfying.

Perlitic fracturing

Concentric perlitic cracks sometimes traverse the nodule like onion skins, evidence of hydration and cooling history.

Microlites & bubbles

You may spot minute magnetite flecks or tiny vesicles; most Apache tears are relatively clear glass compared to scoriaceous lava.

Basalt pebbles

Basalt is crystalline, shows duller luster, and remains opaque even in strong backlight. Fresh breaks lack perfect glassy conchoids.

Slag (industrial glass)

Can be very glassy and bubbly with odd colors (blue/green). Shapes are irregular chunks; context (near old smelters) is a clue.

Black onyx / agate

Cryptocrystalline quartz (Mohs 7) — harder, heavier feel, and often shows banding; under a loupe, texture is sugary/microfibrous, not glassy.

Jet or coal

Much lighter (low SG), duller luster, sooty streak; Apache tears are denser and glass‑shiny on a fresh chip.

Tumbled smoky quartz

Transparent with crystal faces or healed fractures; quartz won’t show the same uniform tea‑brown back‑glow through a black exterior.

Quick checklist

• Backlight = brown glow? ✓
• Glassy conchoidal chips? ✓
• Context: perlite host nearby? Extra ✓

Where they’re found

Classic Apache tears occur in the U.S. Southwest—notably Arizona (perlite‑rhyolite areas around the central ranges), as well as parts of Nevada, New Mexico, Utah, and California. The nodules weather from light perlite beds and collect on slopes and arroyos.

Place‑lore

The familiar name is tied to regional stories told around Arizona’s rugged mesas. However one hears the tale, the respectful practice is to enjoy these stones as Southwestern obsidian with a remarkable back‑glow and to collect thoughtfully where allowed.

Everyday care

• Clean with lukewarm water + mild soap and a soft cloth; dry well.
• Avoid sharp impacts and rapid temperature changes (it’s glass).
• Store separately; obsidian can scratch softer materials and be scratched by quartz.

Jewelry use

• Great for cabochons, beads, tumbled talismans. Protective bezels help.
• For rings/bracelets, opt for thicker domes and mindful wear—chips happen.

On the wheel

• Preform gently; keep cool to avoid “orange peel” texture.
• Pre‑polish through 3k–8k → finish with cerium or tin oxide on felt or leather.
• Chamfer edges slightly; fresh chips are razor‑sharp.

The sun test

Hold a nodule to a bright window or flashlight. The interior glows smoky brown; flow lines may appear like faint currents in tea.

Conchoidals in action

If you have a broken offcut, tilt the chip and watch the Hertzian cone catch the light—curved ripples frozen mid‑shatter. (Do not make fresh chips for fun—your fingers will object.)