Tektite — Earth Glass Born from a Cosmic Strike
Tektites are natural glasses made when a hyper‑velocity impact flash‑melts terrestrial rock, then blasts droplets into the sky. Those droplets cool mid‑flight, splash down across vast “strewn fields,” and weather into sculptural, pitted forms. Think of them as Earth’s own stardust souvenirs—terrestrial in chemistry, cosmic in origin story.
Identity & Naming 🔎
Not a meteorite—an impact glass
Tektite refers to terrestrial glass formed by meteorite impacts, not to space rock itself. Chemistry reflects the local target rocks (usually silica‑rich). The name traces to Greek téktos, “melted.”
Families & cousins
Moldavite is the prized green variety from Central Europe; australites (Australia) are famous for their aerodynamic “button” shapes. Libyan Desert Glass is often grouped as “impact glass”—pale lemon‑yellow silica glass from the Sahara.
How It Forms 🧭
Shock, melt, launch
A hyper‑velocity impact flash‑melts surface rocks and ejects droplets at high speed. The droplets quench in flight, preserving flow lines and bubbles, then rain down over a wide area.
Weathering sculpture
Post‑fall, alkaline/acidic waters etch and pit the surface, carving the “warty,” corrugated look (especially in moldavite and indochinite). Australites also show ablation flanges from atmospheric heating.
Strewn‑field timelines
- Moldavite (Czech): linked to the Ries impact (~15 Ma).
- Australasian field: SE Asia → Australia/Philippines (~0.79 Ma).
- Ivory Coast: tied to the Bosumtwi crater (~1.07 Ma).
- North American: georgiaite/bediasite (~34–35 Ma).
Tektites are impact snapshots: a few seconds of planetary melt frozen into lifelong glass.
Palette & Pattern Vocabulary 🎨
Palette
- Black — classic indochinite/australite look.
- Brown‑smoky — common in larger splash forms.
- Bottle‑green — translucent moldavite.
- Lemon‑yellow — Libyan desert glass (impact glass cousin).
Luster is vitreous on fresh breaks, matte on etched skins. Moldavite glows beautifully in transmitted light.
Pattern words
- Splash forms — drops, dumbbells, teardrops, discs.
- Pitting & sculpture — chemical etching creates “warty” textures and channels.
- Flow lines — schlieren bands from melt movement.
- Flanged buttons — australites with ablation “rims.”
Photo tip: Use raking light to reveal sculpture; backlight thin moldavite to ignite that green.
Physical & Optical Details 🧪
| Property | Typical Range / Note |
|---|---|
| Chemistry | Silica‑rich natural glass (SiO₂ dominant) with Al, Fe, Ca, K, etc.; very low H₂O compared to volcanic glass. |
| Structure / Group | Amorphous (glass) • Impactites |
| Hardness (Mohs) | ~5–6 (glass range; handle as a brittle gem) |
| Specific gravity | ~2.20–2.50 (moldavite often ~2.32–2.38) |
| Refractive index / Optics | ~1.47–1.51; isotropic; commonly shows strain under crossed polars |
| Pleochroism | None (glass) |
| Luster / Transparency | Vitreous; opaque to translucent (moldavite is typically translucent) |
| Cleavage / Fracture | No cleavage; conchoidal fracture; brittle |
| Diagnostics | Flow schlieren, elongated bubbles, lechatelierite wisps; etched/pitted rinds; australites may have flanged rims |
| Fluorescence | Inert to weak (varies) |
| Treatments / Imitations | Common fakes: green bottle/slag glass sold as moldavite; acid‑etched glass to mimic sculpture; molded replicas. Request disclosure. |
Under the Loupe 🔬
Impact textures
Look for flow bands (schlieren), elongated vesicles, and wispy lechatelierite (fused silica). Fresh chips show classic conchoidal shells.
Surface story
Natural etch pits and grooves appear irregular and non‑repeating. Australites may show ablation rims/flanges—aerodynamic re‑shaping during re‑entry.
Fake flags
Moldavite fakes: glassy drips, repetitive textures, mold lines, round “factory” bubbles, very bright neon‑green. When in doubt, get a lab test.
Look‑Alikes & Imitations 🕵️
Obsidian (volcanic glass)
Also glass, but often higher water, smoother skins without impact sculpture. Locality context and surface texture help separate.
Bottle/slag glass
Uniform color, mold seams or casting marks, round bubbles, and sometimes higher SG (lead glass). Sculpture is often etched, not natural.
Scoria/pumice
Highly vesicular, much lighter, and not glassy inside like tektites. Pumice floats; tektites do not.
Libyan desert glass
Impact glass cousin—lemon‑yellow, often higher silica; forms nodules and wind‑polished pebbles rather than splash forms.
Quick checklist
- Glassy, etched/pitted skin with non‑repeating texture?
- Flow lines + stretched bubbles at 10×?
- Locality fits a known strewn field? → Likely tektite.
Strewn Fields & Uses 📍
Where it’s found
- Central Europe: Moldavites (Czech Republic, Germany).
- Australasian field: Vietnam, Thailand, Laos, Cambodia, China, Australia, Philippines.
- Ivory Coast (Côte d’Ivoire) — West Africa.
- North America: Georgiaites (Georgia, USA), Bediasites (Texas, USA).
- Sahara: Libyan Desert Glass (impact glass).
What people make
Natural specimens with original skins for collectors; jewelry (especially moldavite) as cabs or raw shards; inlay and talismans with an unmistakable space‑age story.
Care, Jewelry & Lapidary 🧼💎
Everyday care
- Clean with lukewarm water + mild soap; soft cloth dry.
- Avoid ultrasonics, steam, harsh chemicals, and rapid temperature swings.
- Store separately; quartz and corundum can scuff the surface.
Jewelry guidance
- Great for pendants, earrings, brooches.
- For rings, choose protective bezels/low profiles; respect brittleness.
- Show off natural sculpture or backlight thin moldavite for glow.
On the wheel
- Inspect for internal bubbles/strain; keep cool, light pressure.
- Pre‑polish 600→1200→3k; finish with cerium oxide on felt/leather.
- Preserve original skin when possible—collectors value it.
Hands‑On Demos 🔍
Polariscope strain
Under crossed polars, tektites show strain figures—a quick glass vs. crystal demo. (Quartz would go light/dark with rotation.)
Backlight the green
Place moldavite on a lightbox: its olive‑bottle glow and internal flow lines leap out. A customer‑magnet moment.
From shockwave to showcase—each tektite is a tiny, time‑stamped shard of an ancient impact.
Questions ❓
Is a tektite a meteorite?
No. It’s Earth rock melted by a meteorite impact, then thrown and quenched into glass.
Why are surfaces pitted?
Post‑fall chemical etching and weathering sculpt the rind; australites also show re‑entry ablation features.
How to tell moldavite from green glass?
Look for irregular, non‑repeating sculpture, internal flow lines, stretched bubbles, and trusted locality. Many fakes exist—lab tests help for expensive pieces.
Do tektites contain space material?
They’re mostly terrestrial melt; trace meteoritic signatures can be present but are minor.
Metaphysical note?
Often chosen for transformation & cosmic connection.