Lead sulfide crystal
Chemical formula: PbS
Lead sulfide, also known as galena, occurs naturally on planet Earth. It is an important ore of lead, and forms dull, grayish, cubical crystals of varying size. It is also a natural semiconductor, and as such was vital in the early days of radio, when a single galena crystal was used as a 'detector' for radio waves.
Lead sulfide crystals are a Cybertronian food product, and apparently delicious when combined with savory mercury sauce and flavorful iron filings as garnish for a tasty robot. They are, of course, poisonous and quite inedible for humans. It should be noted that the crystals as shown in Marvel comics emit a greenish glow in the visible spectrum; this may indicate that they are formed from an unknown radioactive lead isotope.
The effect of common gray galena on robot tastebuds is not known.
