I am not sure about where they are from but I know that they can have a biological origin also, like mollusc shells
they are mostly biological in origin, such as mollusc shells or coraline algae.
I just love the beach do you know anything about it's coral reefs? Unfortunatelly I don't know anything about coral reefs, all I know is that beaches are composed by particles made from rock, like gravel, sand, pebbles and others Where do those materials come from?  Are they washed up from the ocean?
The particles can also be biological in origin, such as mollusc shells or coralline algae.