Is onyx a good stone for a bathtub?
Last updated October 2026.
Quick answer
- What onyx is
- banded calcite (also called onyx marble), formed from mineral-rich water
- Look
- translucent; glows when lit from behind or within
- Hardness
- about 3 on the Mohs scale, softer and more brittle than most marble
- Weight
- similar to marble: a 78″ onyx tub is published at 2,000 lb
- Price
- the top of the stone range; rare onyx tubs reach $50,000+ (as of October 2026)
Yes, for a statement bath that is used with care. Onyx is a banded, translucent calcite that glows when lit, and no two blocks look alike. It is softer and more brittle than marble and etches with acids, so it needs gentle cleaning and a sealed finish, and it costs more because large flawless blocks are rare.
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What is an onyx bathtub?
An onyx bathtub is carved from a single block of onyx: a calcite stone laid down in layers from mineral-rich water, which gives it its bands of honey, white, green or red. Its translucency is what sets it apart; light passes into the stone rather than bouncing off it, so the color seems to come from inside.
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How does onyx compare with marble for a bathtub?
| Feature | Onyx | Marble |
|---|---|---|
| Mineral | Calcite, banded | Calcite, recrystallized |
| Look | Translucent, bold bands; glows when lit | Opaque; veining from subtle to bold |
| Hardness (Mohs) | About 3; brittle | About 3–5 |
| Acids | Etches | Etches |
| Weight | Similar to marble | 1,100–2,500 lb for a tub |
| Care | Gentlest; protect the rim from knocks | pH-neutral cleaner, seal yearly |
| Price | Highest; rare onyx tubs reach $50,000+ | About $14,000–$37,000 from US sellers |
Prices are published US prices as of October 2026; see the cost guide.
Is onyx real stone?
Yes. The onyx used for baths and interiors is a natural calcite stone, sometimes sold as onyx marble, Mexican onyx or Egyptian alabaster. It forms in layers from mineral-rich water, which gives it bands of color. It is different from the hard, quartz-based onyx used in jewelry.
Can an onyx bathtub be backlit?
Onyx is translucent, so light passing through it shows its banding. A tub's walls are much thicker than a backlit wall panel, so the glow is softer; lighting is planned with the design, for example LED light in a plinth or recess below the tub.
How much does an onyx bathtub weigh?
About the same as marble of the same size. Stone Forest publishes 2,000 lb for its 78″ honey onyx tub. Check the floor before ordering with our weight and floor-load calculator.
How do you care for an onyx bathtub?
As for marble, but more gently: a pH-neutral stone cleaner and a soft cloth, wipe dry after use, no acidic or abrasive cleaners, and reseal about once a year. Avoid dropping heavy objects on the rim, because onyx chips more easily than marble. Full steps are in our stone bathtub care guide.
Why are onyx bathtubs so expensive?
A tub needs one large block free of cracks, and onyx forms in layers that are often fractured, so usable blocks are rare and much of each block is lost in carving. The stone also takes more care to cut and polish.
Where can you see onyx tubs?
See our onyx bathtubs, each carved to order from a block chosen with you, or ask for a sample in the sample book.