Basalt
Basalt is igneous (volcanic, mafic). In the hand, it rates 5 to 6 (varies) on the Mohs scale, and it runs black and dark gray. Matte black fine-grained volcanic rock, usually riddled with round gas holes when sold as 'lava stone' beads. The most common volcanic rock on Earth, ocean floors, Hawaii, Iceland, everywhere basaltic lava flowed.
The geology.
Basalt carries the formula . It belongs to the, system. The trade files it under igneous (volcanic, mafic).
It sits at 5 to 6 (varies) on the Mohs scale. The surface reads dull to matte. Light behaviour is opaque. Specific gravity runs 2.8 to 3.0 (vesicular lower). The streak is,. It breaks with uneven fracture.
Matte black fine-grained volcanic rock, usually riddled with round gas holes when sold as 'lava stone' beads.
Common cuts are 'lava bead' bracelets, tumbled or raw vesicular chunks.
The origins.
The most common volcanic rock on Earth, ocean floors, Hawaii, Iceland, everywhere basaltic lava flowed.
On value, the database notes: common and very affordable.
Traditional associations.
In energy work traditions, associated with grounding and endurance.
Included for completeness. Tradition is worth knowing about, and it is worth keeping separate from the mineralogy.
Spotting the real thing.
Matte black fine-grained volcanic rock, usually riddled with round gas holes when sold as 'lava stone' beads.
Some 'lava beads' are dyed or are man-made ceramic; natural pores are irregular.
| Looks like | How to tell them apart |
|---|---|
| Black tourmaline | Tourmaline is glassy with striations; basalt is dull and granular |
| Obsidian | Obsidian is shiny glass with conchoidal fracture; basalt is stone-matte |
| Man-made foam/ceramic beads | Synthetic 'lava' beads are unnaturally uniform in pore size and weight |
At-home tests.
These checks cost nothing. Daylight, a 10x loupe and a little patience are the whole kit for basalt.
| Test | What you should see |
|---|---|
| Look for bubbles | Round vesicles (gas bubbles frozen in rock) |
| By eye | Heavier than it looks despite the holes |
| Magnet check | May weakly attract a strong magnet (magnetite content) |
If these checks leave you unsure, that is what appraisers are for. Do not file, heat or soak a piece to find out.
Care & handling.
At 5 to 6 (varies) on the Mohs scale it handles careful wear but scratches against quartz and dust. Store it separately and take rings off before rough work.
It breaks with uneven fracture, which is worth knowing before you set it or drop it.
Most damage happens during cleaning, not wearing. Avoid steamers, ultrasonic tanks and anything from under the sink.
A deeper look.
Extended detail on composition, sourcing, authentication and market value.
The physical record
The formula on record is . Crystal system:,. Specific gravity: 2.8 to 3.0 (vesicular lower). Streak:,. Cleavage and fracture: Uneven fracture.
How it reaches the market
The most common volcanic rock on Earth, ocean floors, Hawaii, Iceland, everywhere basaltic lava flowed.
What it gets confused with
Black tourmaline: Tourmaline is glassy with striations; basalt is dull and granular. Obsidian: Obsidian is shiny glass with conchoidal fracture; basalt is stone-matte. Man-made foam/ceramic beads: Synthetic 'lava' beads are unnaturally uniform in pore size and weight.
What it is worth
Common and very affordable.
Where buyers get caught
Some 'lava beads' are dyed or are man-made ceramic; natural pores are irregular.
One more thing
The dark plains of the Moon visible from your backyard are basalt flows.
An education-first guide.
There is nothing to buy on this page. Basalt is not part of our catalogue, and the guide is here anyway because somebody searching the name deserves a straight answer.
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