Main-belt asteroid 354 Eleonora was discovered on this day in 1893 by Auguste Charlois. It’s a stony (S-type) asteroid of approximately 154 km across, rotating with a period of about thirteen and a half hours. It can reach a magnitude of +9.3 at opposition.
Stony asteroids like Eleonora can often be shown by spectroscopic studies to contain olivine, a magnesium iron silicate that becomes known as peridot when of sufficient quality to be cut into a gem (sometimes being mistaken for emerald) and pyroxenes, a large group of mineral found almost everywhere. The upper mantle of the Earth is composed mainly of olivine and pyroxene.
Eleonora is one of those titillating asteroids whose name is generally thought to be of unknown origin. But somebody must have written it down somewhere; it’s just a matter of finding it. There was, as it happens, a very famous Eleonora around at the time of the discovery: Eleonora Duse, the Italian actress, was busy making a name for herself on the stages of the world, and would have been well known to Charlois. She’s going down as a definite “maybe”.