It’s statistically improbable, but possible
Almost all minerals you’ll find in the wild are bog standard ones.
Tangent about slate, shale, and clay. One of the diagnostic properties is “grain size”. To determine if soil is clay or silt sized particles, one of the common tests is: rub it on a tooth – if it feels smooth, the particles are clay sized. Slate and shale are clay minerals, and will feel smooth on a tooth if rubbed in the direction of the grain. If it doesn’t feel smooth, then it’s a siltstone or similar.
It’s statistically improbable, but possible Almost all minerals you’ll find in the wild are bog standard ones.
Tangent about slate, shale, and clay. One of the diagnostic properties is “grain size”. To determine if soil is clay or silt sized particles, one of the common tests is: rub it on a tooth – if it feels smooth, the particles are clay sized. Slate and shale are clay minerals, and will feel smooth on a tooth if rubbed in the direction of the grain. If it doesn’t feel smooth, then it’s a siltstone or similar.