Rock Identifier
Banded Slag Glass (Leland Blue/Frankfort Green style) (Anthropogenic Glass Specimen (Amorphous Silicon Dioxide with impurities)) — mineral
mineral

Banded Slag Glass (Leland Blue/Frankfort Green style)

Anthropogenic Glass Specimen (Amorphous Silicon Dioxide with impurities)

Hardness: 5.5-6 (Mohs); Color: Black with vibrant orange/neon band; Luster: Vitreous to dull; Structure: Amorphous (non-crystalline); Conchoidal fracture; Specific gravity: approx 2.4-2.8

Hardness
5
Color
Black with vibrant orange/neon band
Luster
Vitreous to dull
Identified More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App StoreGoogle Play

Physical properties

Hardness: 5.5-6 (Mohs); Color: Black with vibrant orange/neon band; Luster: Vitreous to dull; Structure: Amorphous (non-crystalline); Conchoidal fracture; Specific gravity: approx 2.4-2.8

Formation & geological history

Formed as a byproduct of iron smelting or glass manufacturing where molten waste was dumped and rapidly cooled. Most specimens date from the mid-19th to early 20th centuries in industrial lakeside regions.

Uses & applications

Primarily used for lapidary work, jewelry (cabochons), and as a collector's item due to its unique aesthetic patterns.

Geological facts

While not a natural 'rock,' these specimens are highly sought after by 'rockhounds' and are often treated as honorary gemstones. The specific vibrant orange band in this piece is rarer than the common blue or green varieties.

Field identification & locations

Identify by looking for air bubbles (vesicles), conchoidal (glass-like) fractures, and distinct artificial banding. Found commonly on beaches near old iron foundry sites like those in the Great Lakes region.

More like this

Other mineral specimens

Sandstone (with potential mineral staining/concretions) (Arenite (SiO2 based)) — sedimentary

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary
Schist (Schist) — Metamorphic

Schist

Schist

Metamorphic
Epidote (Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)) — metamorphic

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic
Nephrite Jade (Nephrite) — Mineral/Rock

Nephrite Jade

Nephrite

Mineral/Rock
Banded Gneiss (River Rock/Pebble) (Gneiss (specifically a banded variety often found as a river rock)) — Metamorphic Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock
Biotite Schist (Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]) — metamorphic

Biotite Schist

Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]

metamorphic