Sensory descriptor
Wet stone
A cool, damp, faintly mineral impression, in cider a product of low-level sulphur compounds and high acidity rather than of minerals.
Also called Flint, Wet slate.
- Aroma family
- Earthy
- Does it indicate a fault?
- It depends on the style it is met in
What causes it
Nothing mineral in a cider is volatile, so this perception is not caused by the minerals it appears to name. The most plausible established mechanism is a combination of sub-threshold sulphur compounds — benzenemethanethiol and related thiols, and traces of hydrogen sulphide — with high acidity and an absence of fruit ester. The perception is largely one of what is missing: a cider stripped of esters by cool clean fermentation and sterile filtration, carrying sharp malic acidity and a whisper of reduction, reads as stony because there is nothing else in the way.
The compounds responsible
Where the molecule is established. Some descriptors in this lexicon name a compound the compound register does not yet hold a record for; those are named in the cause above instead.
Mercaptans
What hydrogen sulphide becomes if it is left alone: onion, garlic and rubber notes that are far harder to remove than the gas they came from.
Hydrogen sulphide
The rotten-egg gas a nitrogen-starved yeast produces, detectable at concentrations too small to measure easily, and removable only if it is caught before it becomes something worse.
Malic acid
The acid of apples, which supplies almost all the sharpness a cider has and, through pH, decides how vulnerable that cider is to everything that could spoil it.
Sulphur dioxide
The antimicrobial and antioxidant on which most modern cidermaking depends, and whose effectiveness collapses as pH rises — which makes every sulphiting decision a pH decision first.
What raises it
Processes that increase this character, or preserve it where it would otherwise be lost.
Sterile filtration
Membrane filtration at a rating that retains viable yeast and bacteria, which is what allows a sweet cider to be shelf-stable without heat or preservative — provided the filling that follows is aseptic.
Cold maturation
Holding cider at low temperature so that it settles bright, sheds colloidal material and stops changing microbially, without any additive or treatment being applied.
Oxygen management in fermentation
Giving the yeast the oxygen it needs early to build viable membranes, then excluding it once fermentation is under way and especially once it slows.
Sulphiting
Adding sulphur dioxide to juice to suppress spoilage organisms and oxidative browning, at a level that only means anything once the juice pH is known.
Where it is usually met
Fruit and styles this character is recorded in. A record here is where the descriptor is commonly found, not a claim that every example shows it.
About Wet stone
This descriptor is included with a caution attached, because it is the point at which wine vocabulary most often enters cider writing without a mechanism. Minerality as a transferred flavour of soil is not supported by any evidence in either drink, and CiderHQ does not describe it that way.
What the word usefully names is a real and recognisable impression in very dry, low-ester, reductively handled cider, and describing that as wet stone is reasonable as long as its cause is stated. Where the sulphur component rises, the accurate descriptor becomes flinty or, further on, struck match.
Others in the earthy family
Farmyard, wet stone, damp cellar, mushroom.
Farmyard
The composite animal-and-straw note of volatile phenols with short-chain fatty acids, central to traditional farmhouse character.
Corked
The damp-cardboard mustiness of TCA from a contaminated cork, affecting single bottles rather than batches.
Musty
A stale, mouldy, damp-loft note from fungal metabolites on the fruit or in storage, recorded as a taint.
Damp cellar
A cool, musty, faintly fungal note from moulds and film organisms in the maturation environment.
Mushroom
A distinctly fungal note from 1-octen-3-ol, produced by moulds on the fruit or by film yeast on the surface.
Forest floor
Damp leaf, soil and fungal character in aged cider, from the combination of oxidised phenolics with low-level fungal volatiles.
What people ask next
Questions readers ask about the things this page mentions. Each one goes to the section that answers it rather than to a page written to receive the question.
- Does cider contain sulphites — Most does. Sulphur dioxide is added to protect juice and finished cider, and fermentation itself produces a small amount even when none is added. European labels must declare it above 10 mg per litre.
- What is malic acid and why does it matter in cider — Malic acid is the acid of apples and supplies almost all the sharpness a cider has. It also sets pH, which decides how well sulphite works and how exposed the cider is to spoilage, so it does far more work than its taste suggests.
- Why is sulphite added to cider — Sulphur dioxide suppresses spoilage bacteria and wild yeast before fermentation and protects the finished cider from oxidation. How much of it is active depends strongly on pH, which is why low-acid juice is harder to protect.
- How do you pour bottle conditioned cider — Stand the bottle upright for a day, chill it, and pour in one continuous movement, stopping when the sediment reaches the shoulder. Some traditions deliberately rouse the sediment instead, and both are defensible.
- Does cider need oxygen to ferment — Yeast needs a little oxygen early on to build the sterols it uses to stay healthy, but the ferment itself is anaerobic. After the first days oxygen is a liability, because it feeds acetic acid bacteria and oxidises the cider.
- Does carbonation change how cider tastes — Yes. Dissolved carbon dioxide forms carbonic acid, so a sparkling cider tastes sharper than the same cider still, and the bubbles carry aroma upwards and scrub fat from the palate.
Where to go next
- The sensory model — The thirteen structural dimensions and the twenty aroma families, in full.
- Compounds — The chemistry behind the words.
- Troubleshooting — When a perception turns out to be a problem, this is where it is diagnosed.
Sources
What this page rests on. Where a source is marked as registered rather than read, CiderHQ is recording that the body is authoritative on the subject without claiming to have worked through the document itself. See our evidence policy for what each state means.
The Science of Cidermaking and associated technical writing
Andrew Lea · reference work · passage verified 2026-08-24
Written by a food chemist who worked at Long Ashton on apple phenolics. Unusual among specialist cider writing in that it is primary-research-adjacent: the author is describing work he did, and cites the literature. This is why it is registered at tier 1 for chemistry while a general cider book is not.
Peer-reviewed literature on apple phenolics and cider sensory perception
Various journals · peer-reviewed literature · registered as competent for this subject
Registered as a class rather than as one paper, because the mechanisms CiderHQ describes — tannin chain length driving the split between bitterness and astringency, salivary protein precipitation, enzymatic browning — are established across many studies rather than resting on any single one. Individual papers are cited where a specific number is quoted.
Washington State University cider research programme
Washington State University Northwestern Washington Research and Extension Center · university · passage verified 2026-08-24
The single most useful open cider dataset CiderHQ has found. The programme’s cultivar performance database gives juice chemistry, orchard behaviour, bloom and harvest timing and cider-maker tasting notes for 73 cultivars grown at one maritime site over fifteen years, and — unusually — publishes its classification thresholds alongside its figures, so the classification can be checked rather than taken on trust. It also states outright that its results diverge from the English ones. Read in full on 2026-08-24 and transcribed into `data/trials/wsu-mount-vernon.ts`; four published figures were found to be impossible and are withheld there with their reasons.