Black Agate Tumbled Stone

Agate is chalcedony - microcrystalline quartz, SiO₂, Mohs 7 - that filled a cavity in volcanic rock layer by layer, each band of silica laid down on the one before. Black striped agate reads as deep black crossed by fine parallel bands of grey and white.

The banding is the whole character: concentric or straight lines that map the cavity’s filling, sharp where the layers ran fine. No two beads carry the same sequence.

The black is deep and even, the grey-white bands fine against it; some beads read nearly solid, others carry several parallel lines drawn close. The contrast of dark ground and pale band is what the stone is cut and polished for.

Asked often

Are the bands natural?
Yes - the banding is the record of how the agate filled its cavity, layer by layer, as the silica was laid down. Each bead is cut from a different part of that layered fill, so no two match.

How is it different from onyx?
Both are banded black chalcedony. Onyx is the solid black layer alone; striped agate keeps the visible grey-white banding across the bead. Same mineral, more pattern shown.

Why is every bead different?
Each bead is cut from a different part of the agate’s layered fill, so the sequence of bands is unique to it. The variation is the stone.

How do I look after them?
Wipe with a soft cloth. Hard-wearing at Mohs 7; keep them together in a pouch so they do not knock against harder stones.

1. Carried in a pocket or a bag, or held in the hand.
2. Kept in a small dish, on a desk, or on a shelf - each stone is a little different.
3. Wipe with a soft cloth; hard-wearing at Mohs 7.

Each stone is tumble-polished and unique, so a set varies a little stone to stone. Many keep a stone where they will see it each day, or carry one in a pocket; that is a matter of preference.

Pocket stones to keep and carry. Wipe with a soft cloth; hard-wearing at Mohs 7. Keep them together in a pouch so harder edges do not scratch softer stones.

• Stone: Black Agate · banded black chalcedony
• Hardness: Mohs 7
• Character: Deep black · some banded grey-white
• Lustre: Vitreous · takes a high polish
• Form: Tumbled stones · polished, each unique · sold in a set
• Origin: India
• Care: Wipe with a soft cloth · keep dry

Agate is named for the river Achates in Sicily, where Greeks gathered it more than two thousand years ago, as Pliny records. Banded agate was carved into cameos, seals, and beads across the ancient Mediterranean, prized exactly for the contrast of its layers.

Across many cultures the banded dark stone was carried as a steadying, sober token - named here as what people believed. The bands are the stone’s own record; what they settle is the wearer’s.