Here are some snapshots of a fountain pen that I own but do not know the provenance of. It was purchased new in the late 80s, that's all I have on its vintage.
The pen is rather short when capped, but heavy. The barrel -- indeed, everything but the ink-cartridge assembly on the nib portion -- seems to be solid brass, lacquered or enamelled in black. That lacquer is now flaking off, primarily where the cap portion fits back onto the (smaller, lighter) nib-and-ink-cartridge portion. The nib appears to be gold, though it has no content markings. It bears the text "IRIDIUM POINT W-GERMANY".
The pen takes standard international cartridges, and can only accomodate the one connected to the nib; there's no room for a spare.
(A warning: these images are all roughly 160kb)
First, a photo of the fully-capped pen.
Next, the cap removed and placed on the other end, ready to be used.
Finally, the two halves, separately.
If you have any idea what this pen is, please write me at firstname.lastname@example.org. Thanks!