Don't discount the basic commodities! Here's a few I whipped up below. I was inspired by Gallia's fossil fuels among other things...
PALLADIUM
Palladium is a precious silvery-white metal. It finds many uses, such as in radiation shield alloys and as a catalyst in fuel cells. It is also beginning to supplant gold and platinum in the use of jewellry, owing to its sturdiness and the extreme rarity of the other two metals in Sirius.
XENON
Xenon is a colorless, odorless noble gas. Its uses are many and varied -- lighting flashtubes, a fuel in ion engines, a stimulant in lasers, and an anesthetic, just to name a few. Xenon is a rare component in the atmosphere of many planets, but can be found in relatively abundant in some space-borne pockets.
COAL
Coal is the remains of ancient organic material, compress into a rock-like form. It exists in relative abundance on many life-bearing planets. The use of coal was abandoned centuries ago, but it has enjoyed a resurgence of late. It can be burned to generate energy in a pinch, although this is a "quick and dirty" method. More commonly it is gasified into CO and elemental hydrogen, from which fusion isotopes can be extracted.
LNG
Liquefied Natural Gas is a mixture of methane, along with trace ethane and longer chain hydrocarbons, compressed into liquid form for easy storage. Like coal it is a byproduct of organic decay, and can generate energy either through direct combustion (somewhat more cleanly than coal), or reduced to hydrogen and its fusible isotopes. Unlike coal, LNG components can be found in space-borne gas pockets as well as on terrestrial planets.
