Apache Tears — Little Obsidian Orbs with a Sunlit Secret
Apache tears are small, rounded pebbles of obsidian that hide a warm surprise. In room light they read inky black; hold one to the sun and the interior lights up tea‑brown to cola‑amber. They weather out of pale perlite like raisins from a scone (geologists get hungry, too). Smooth in the hand, sharp if broken, these nodules are pocket‑sized windows into a lava’s quick‑chilled heart.
Identity & Naming 🔎
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.
How Apache Tears Form 🧭
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.
Recipe: hot rhyolitic melt → glass → hydration rind → weathering → a pocketful of “tears.”
Colors & Pattern Vocabulary 🎨
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.
Physical & Optical Properties 🧪
| Property | Typical Range / Note |
|---|---|
| Composition | Rhyolitic volcanic glass (SiO₂‑rich; minor Fe, Mg, Ca, Na, K) |
| Structure | Amorphous (no long‑range crystal order); may host tiny microlites |
| Hardness | ~5–5.5 (can scratch window glass; quartz can scratch it) |
| Specific gravity | ~2.3–2.5 (light compared to most dark rocks) |
| Cleavage | None; breaks with conchoidal fracture |
| Luster | Vitreous on fresh surfaces; sub‑vitreous to matte when weathered |
| Transparency | Opaque to translucent brown in thin edges/strong backlight |
| Stability | Excellent indoors; avoid extreme thermal shock (it is glass) |
Under the Loupe 🔬
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.
Look‑Alikes & How to Tell 🕵️
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 ✓
Localities & Lore 📍
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.
Care & Lapidary Notes 🧼💎
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.
Hands‑On Demos 🔍
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.)
Small joke: an Apache tear is a rock that insists on dramatic lighting. Direct sunlight only, please.
Questions ❓
Is “Apache tear” a mineral?
No—it’s a form of obsidian (volcanic glass). The name refers to the rounded nodules, not a new species.
Why do mine look black indoors but brown outside?
Obsidian is nearly opaque in normal light, but thin edges transmit brown. Bright back‑lighting reveals it beautifully.
Are they the same as onyx or jet?
No. Onyx is quartz (harder, often banded). Jet is organic (lightweight, duller luster). Apache tears are glassy obsidian nodules.
Can I cab an Apache tear?
Yes—orient for a high dome and polish with cerium/tin oxide. Expect superb luster and that signature warm glow on thin edges.
Any safety concerns?
Just one: fresh chips are sharp. Handle broken pieces with care and keep them away from pockets that like to eat fingers.