Is Obsidian Brittle? Hardness, Toughness and Daily Wear
Obsidian hardness, toughness and bead shape explained, with a comparison of quartz and volcanic glass, polished surfaces and everyday care.
In this field note
The word brittle describes how a material breaks under force. Obsidian can also take a fine polish, which gives a finished bead its clear surface reflections. Both properties belong to the same volcanic glass.
Hardness, toughness and shape each describe one part of a finished piece. The complete guide to obsidian covers its formation and varieties; here, the focus is how those physical properties relate to a polished bead.
How do hardness and toughness differ in obsidian?
Obsidian has a Mohs hardness of about 5 to 5.5. The scale ranks materials by which can scratch another. Toughness describes resistance to breaking, chipping and cracking under force. These properties are assessed separately.
Obsidian forms as silica-rich lava cools without developing a regular crystal lattice. Its glassy structure is amorphous. A broken surface can curve like the inside of a shell, the form known as conchoidal fracture. This is a description of the material, visible in natural and worked specimens.
Mohs values rank scratch resistance. The difference between two adjacent numbers is not constant. The bracelet hardness chart places obsidian alongside quartz and other jewellery materials.
How does shape change the appearance of obsidian jewellery?
A polished round bead has a continuous curve. A faceted bead divides its surface into flat planes; a cabochon has a rounded upper face and a base designed for a setting. These forms reflect the same light in different ways.
| Form | Surface | Visible feature |
|---|---|---|
| Polished round bead | Continuous curve | A highlight moves across the bead |
| Faceted bead | Flat planes | Separate reflections on each facet |
| Thin tablet or slice | Broad faces | A wide view of the material |
| Cabochon | Domed face | A curved reflection above the setting |
On a finished strand, the polish and the roundness of the beads are easy to compare in one fixed light. Turn the strand slowly and look across several beads, allowing their surfaces to pass through the same angle.
How does obsidian compare with quartz in a strand?
Quartz has a Mohs hardness of 7, above obsidian at about 5 to 5.5. Quartz is crystalline; obsidian is natural glass. Both can take a polished surface and appear in mixed-material strands.
Smoky quartz can transmit light through its brown or grey body. Dark obsidian often gives a stronger surface reflection. The smoky quartz versus obsidian guide compares their appearance and material structure.
How should you wear and care for an obsidian strand?
A polished obsidian strand suits ordinary daily wear. Remove it for sport or manual work and store it separately from harder jewellery; the Care & Durability Checker gives the full care guidance.
BE. grades stone with Crystal 4T™, assessing Transparency, Tone, Texture and Treasure. The Stone Origin Record records the material lot and its treatment status. Each product page gives the construction of that strand.
Frequently asked questions
Q1.Does obsidian break easily?
Obsidian is brittle, so sufficient impact can break it. Its use in polished jewellery also reflects its ability to take a smooth, glassy finish. Hardness and toughness describe separate properties.
Q2.What is obsidian on the Mohs hardness scale?
Obsidian is commonly listed around 5 to 5.5 Mohs. That number describes relative scratch resistance and does not measure resistance to chipping.
Q3.Can I wear an obsidian bracelet every day?
Yes. Follow the activity and storage guidance in the Care & Durability Checker.
Q4.Can round obsidian beads chip?
Yes. Rounded shape leaves fewer exposed corners, while the material retains the fracture properties of volcanic glass.
Q5.Can obsidian and quartz be worn in the same bracelet?
Yes. Quartz and obsidian are both used in mixed-material strands. Their different hardness values remain relevant to care and storage.
Q6.Is chipped obsidian safe to keep wearing?
Set aside a strand with a sharp or loose damaged area and have the piece checked before wearing it again.
References
Field Notes.
One stone at a time: its geology, and how to read quality. The Stone Buying Checklist comes with your first email.
By subscribing you agree to receive emails from BE. Unsubscribe anytime.
Sent. Check your inbox.