just a WAG, but i would think its related to apples.. pommes in frence, and pommegranites (seed apples) and other pom(p) words..i know apples are not a big crop in italy, (generaly, apples like it cooler) but red/apple/pom seems a likely connection. there are many places with red clay -which is often red/brown, but i don't know of any red lava's.. (jasper is metamorphic right?)