The video below introduces an unsual sound art piece based on a Raspberry Pi. Named Ra – as in the sun god of the ancient Egyptians – it’s a little like a record player, except that it doesn’t play records; instead, it “plays” pyrite discs, a rare kind of mineral deposit. Its creator is Dmitry Morozov, a “Russian media-artist, musician and engineer of strange-sounding mechanisms.” He describes Ra as a sound object/synthesizer.

Usually, pyrite, or fool’s gold, forms cuboid crystals. But in coal mines near Sparta, Illinois (and nowhere else on Earth, so far as anyone knows), it forms discs with grooves radiating out from the centre, and these are known as pyrite dollars or pyrite suns. Ra uses a laser to scan the surface of a pyrite disc as it is turned, and represents the mineral’s superficial irregularities as sound.

Cuboid and discoid crystals of pyrite

Dmitry was inspired to create this piece of sound art by his reading about the preservation of the earliest sounds recorded in fragile media such as wax. The projects he was learning about all used lasers, and he set out to make his own laser sound reader that would be able to produce sound from unorthodox irregular surfaces.

A DIY laser pickup “reads” the surface of the pyrite as it is turned by a stepper motor. Its output is passed to a Raspberry Pi which synthesizes it and applies various filters and effects, and plays the resulting sound through a single speaker. Ten control knobs and nine switches allow a user to alter the speed and direction of the disc’s motion and the parameters of the sound synthesis and processing carried out by the Raspberry Pi. There’s a little more information on Dmitry’s website, and the object itself is in the Sound Museum in St Petersburg.

Ra, a sound art piece that synthesizes sound from the surface irregularities of pyrite disks

As you’ll have heard if you played the video above with sound, the audio representation that Ra makes of the patterns in the material is an eerie cinematic sci fi-like soundtrack with with long, sustained tones interspersed with short and distinctive motifs of rhythm and melody that alter as they repeat. It’s unexpectedly appealing, to me at least, and leaves me wondering what the synthesizer would make of other substrates.