I think the elements are identifiable. I guess that such identifiable elements were formed into the never-before-seen compounds is what makes it so startling.
For example: “…And a compound consisting mainly of phosphorus and nickel, with no iron - a mineral composition never seen before, not on Earth, and not in extraterrestrial materials…”
I guess no one knows of a technique for creating that compound? Or no one knows how such a mineral compound could be formed naturally under geologic forces? (If I’m even saying that right) Because such examples have not been found on anything nor anywhere else on earth; nor in recovered samples from the moon; nor in other recovered meteorites…?
I think there are processes for man to make most any compound so long as they can nauturally stick together, but is hugely expensive for small qauntities. I guess these appear to be naturally made, but are not known to naturally exist anywhere else. Maybe the planet/entity they came from didn’t have the same full table of elements to choose from, or at least not in the same normal quantities typically found close to here, so the bindings were different. Another guess would be from far far away where maybe that is normal.
I have unidentifiable objects in my socks!