Marble, limestone and travertine: the differences that matter.
They are the same mineral at three stages of the same story, which is why lemon juice marks all three. The differences are in density, texture and how each takes a finish, and those decide how it is looked after.
Limestone is a sedimentary rock of compacted shells and sea-floor sediment: calcium carbonate. Travertine is limestone laid down by mineral springs, so it is full of gas holes. Marble is limestone that has been cooked and squeezed until it recrystallised, denser and harder, with the veining that came from the impurities being moved around. Same mineral, three structures.
How each looks
Marble: crystalline, often veined, takes and holds a high polish. Whites, greys, creams, greens, blacks. Every slab different.
Limestone: uniform, soft in colour (creams, greys, taupes), sometimes with fossil traces. Usually sold honed; some dense varieties will take a polish and most will not hold one.
Travertine: banded, warm, with visible pores and voids, sold filled or unfilled, honed or tumbled, occasionally polished.
What they share
All three etch under acid: lemon, vinegar, wine, most sprays. All three scratch under grit. All three are porous and want a penetrating sealer. A sealer slows stains on all three and stops etching on none of them.
Where they differ in use
Porosity. Travertine and limestone drink more than marble, so they stain faster, need sealing more, and show darkening more readily on their honed faces. Travertine's open holes also hold dirt and reopen as the fill wears.
Hardness and finish. Marble is the hardest of the three and polishes to a mirror; a polished marble floor can be restored to that mirror indefinitely. Limestone is softer and generally lives honed; forcing a gloss on a soft, open limestone is a finish that fails within months. Travertine takes a hone well and a polish only in denser grades.
Repair. Marble repairs demand the most colour work because the polish and the veining show every difference. Travertine takes filler in its voids by design. Limestone repairs sit in a matte surface and are the easiest to hide.
Telling them apart
Veining and a crystalline sparkle on a fresh edge say marble. Visible pores, holes or a banded structure say travertine. A uniform, matte, fine-grained stone in a warm neutral says limestone. A drop of water darkening quickly says the stone is open (or unsealed); a bead says dense or sealed. If you are unsure, a photo of the surface and an edge is usually enough for a first answer, and the stone tests page has the water and the acid tests laid out.
The stones that are not in this family
Granite is silica and feldspar: harder, acid-resistant, slower to polish. Terrazzo is stone chips in a cement or resin binder, and the cement etches like marble. Porcelain is fired clay, dense and glazed, and its grout is the porous part. Engineered stone is quartz in resin and is a different job again. Sandstone is silica grains in a mineral cement, cleaned and sealed rather than polished. Each of those has its own page on this site; the three calcium stones share the rules above.
On this site
Related questions.
I do not know what kind of stone I have. Does that matter?
Not for getting a quote. Send a photo and we can usually tell, and the difference between marble, limestone and travertine changes the method more than the price. If you want to check yourself: marble is usually veined and takes a high polish; limestone is more uniform and often honed; travertine has visible holes; granite is speckled and much harder; engineered stone is uniform with no natural veining and does not etch. A drop of lemon juice on an inconspicuous spot will etch marble and limestone within minutes and do nothing to granite or engineered stone. Wipe it off straight away either way.
What is the difference between honed and polished, and which should I choose?
Polished is the mirror finish; honed is matte. Both are produced by the same abrasive sequence, stopped at different points. Polished shows the depth and colour of the stone at its best and reflects light, and it also shows etching and wear more readily. Honed hides small marks, gives a softer look, and is the usual choice for floors in busy houses and for travertine. Neither is more durable than the other in the stone itself; the difference is in how visible wear is. If you had polished and are tired of seeing every mark, honing is an option. If you had honed and want the depth back, polishing is the same work in the other direction. There is a middle setting as well. Stopping the sequence short of a full polish gives a low sheen that lifts the colour without becoming a mirror, which suits a kitchen where reflections of downlights are the thing people find tiring.