Coins of the pound sterling also became known as a "pound". (240 actual pennies, however, weighed only 5400 troy grains, known as tower pound, a unit used only by mints. The tower pound was abolished in the 16th century.) The silver penny remained the primary unit of coinage for about 500 years. The purity of 92.5% silver (i.e., sterling silver) was instituted by Henry II in 1158 with the "Tealby Penny" — a hammered coin. Over the years, the penny was gradually debased until by the 16th century it contained about a third the silver content of a proper troy 24 grain pennyweight. By 1915,
Presolar grains Presolar grains Presolar grains are interstellar solid matter in the form of tiny solid grains that originated at a time before the Sun was formed (presolar: before the Sun). Meteoriticists often use the term to represent "stardust", grains that originated within a single star and which they extract from meteorites for study. Because most interstellar grains are not stardust from a single star, however, being instead interstellar cloud matter accreted by smaller presolar grains, most presolar grains are also not stardust. Logically, all stardust are presolar grains; but not all presolar grains are stardust. This confusing terminology is heavily entrenched