Mahogany Obsidian: A Guide to the Volcanic Glass

Mahogany obsidian is a natural volcanic glass, not a crystal — it forms when silica-rich lava cools too quickly for a crystal lattice to grow. Its warm reddish-brown streaks come from iron oxides swirled through the black base. The USGS volcanic-glass overview explains the geology in plain terms.

At a glance

• Type: Volcanic glass (amorphous)
• Mohs hardness: 5–6
• Color: black with rust-red mahogany banding
• Sources: western US, Mexico, Iceland, Armenia

How it wears

Because obsidian is a glass, it doesn't scratch the way crystalline stones do — it chips. A hard knock against a countertop or a dropped piece on tile can produce a conchoidal fracture (a shell-shaped flake). Ours are polished to a deep gloss and hold up to daily wear against skin and fabric, but obsidian pendants are worth taking off before physical activity.

Cleaning and storage

Obsidian is non-porous — a soft cloth or the warm-water method works. Store away from harder stones so the polished face stays glossy. Our full stone care guide covers the details.

Meaning and use

Historically, obsidian was worked into some of the earliest cutting tools — its fracture produces edges sharper than surgical steel. In modern jewelry it's associated with grounding and protection, though we sell it because the mahogany banding is genuinely beautiful and no two pieces are identical.

Pairing

Warm tones — brass, copper, warm silver, tiger's eye, jasper — all sit well with mahogany obsidian. See red jasper for a complementary earth-tone pairing.