A shallow onyx marble bowl, polished through the body with the natural edge left raw around the rim.
Those bands are layers. The stone builds up where mineral-rich water deposits calcium carbonate a thin film at a time, and the rim is the one face where you can see that sequence in cross-section. Polishing it smooth would have taken away the only part that shows how the stone was made.
Rock: Onyx marble, a banded travertine
Composition: Calcite (calcium carbonate, CaCO₃)
Type: Sedimentary, deposited in successive layers from cold groundwater
Origin: Mexico
Hardness: 3 on the Mohs scale; soft, and scratched by most things harder than a fingernail
Treatment: None
Dimensions: 16.5 x 16 x 21 cm
Weight: 955 g
Note: Keep acids off it and out of it. Vinegar, lemon juice and household cleaners will etch the surface, so it is a bowl for dry things rather than food
You will receive the exact piece photographed.