Can a Rock Be a Musical Instrument? Some of Them Ring Like Bells
By the BrainSnail editorial team. How these articles are written and checked, and how to tell us when one is wrong.
Stones of the right kind, struck in the right place, produce clear sustained notes. Sets tuned to a scale have been made across the world and some are thousands of years old.
Why some stones ring
A struck object rings if it is stiff, dense and internally uniform, so that vibration travels through it without being absorbed by cracks, voids or loose grains. Fine-grained igneous and metamorphic rocks, particularly certain basalts, hornfels and some limestones, meet those conditions well, while sandstone and weathered rock generally do not. Shape matters as much as material, since a long thin bar rings far better than a lump, and the pitch depends on its length, thickness and density in the same way a metal bar does. The best stones sustain a note for several seconds, which is comparable to a small bell.
Where they have been made
Sets appear independently in many places:
- •Chinese chime stones, hung in tuned sets, from over three thousand years ago
- •Vietnamese sets dated to the neolithic, found in the central highlands
- •Indian ringing pillars and struck stones at several temple sites
- •African rock gongs, natural boulders struck for ceremony and signalling
- •European examples built as museum instruments in the nineteenth century
- •Modern concert instruments built from selected quarried stone
The Victorian instrument
A remarkable example was built in Cumbria in the 1840s by Joseph Richardson, a stonemason who spent thirteen years selecting and shaping hornfels from the local fells into a set of more than sixty tuned bars arranged like a keyboard instrument. The family toured with it, performed for Queen Victoria in 1848, and the instrument survives in a museum in Keswick and is still played. The story illustrates what the material demands, since tuning a stone bar means removing material carefully and irreversibly, and taking off too much ruins a bar that took days to find and shape.
How a bar is tuned
Tuning works the same way for stone as for the metal and wooden bars of other instruments, and knowing the rule explains why the bars of a xylophone are undercut. Shortening a bar raises its pitch. Removing material from the middle of the underside lowers the fundamental, because it reduces stiffness where the bending is greatest. Removing material near the ends raises it. Skilled tuners use both, adjusting the fundamental and then the overtones separately so that the higher modes fall at musically useful intervals rather than at the awkward ratios a plain bar produces. Every removal is permanent, which is why tuners work slowly and check constantly.
The problem with rock gongs
Naturally ringing boulders present archaeology with a genuine difficulty, because establishing that one was used deliberately is much harder than finding one that rings. Struck stones carry cup-shaped marks where they have been hit repeatedly, and those marks are the main evidence, but similar marks are produced by ordinary tool use, by natural processes and by recent visitors. Association with rock art, with paths or with other archaeology strengthens a case. Dating is close to impossible, since a percussion mark cannot be dated directly. The result is that many claimed examples are plausible rather than demonstrated, and the field is careful about the distinction.
The takeaway
Stiff dense uniform rock rings when struck, and a long thin bar of it behaves much like a metal one, with pitch set by length and thickness. Chinese chime stones go back over three thousand years and Vietnamese sets to the neolithic. A Cumbrian mason spent thirteen years building a tuned set of over sixty bars in the 1840s. Proving a natural boulder was used as an instrument is very hard.