ADJ.
rare
VERB + PHOSPHINE
gas
PREP.
in, on
ADV.
only
noun
A toxic gas, chemical formula PH₃.
Any alkyl or aryl derivative of this compound, PR₃ (where at least one R is not H),
Chrysaniline, often in the form of a salt.
An international team of astronomers Monday announced the discovery of a rare gas molecule — phosphine — in the clouds of Venus.
On Earth, phosphine is only made industrially or by microbes that thrive in oxygen-free environments.