Chalcedony to as prase. However, the term prase is also used to describe green quartz, and to a certain extent is a color-descriptor, rather than a rigorously defined mineral variety.) Blue-colored chalcedony is sometimes referred to as "blue chrysoprase" if the color is sufficiently rich, though it derives its color from the presence of copper and is largely unrelated to nickel-bearing chrysoprase. Heliotrope is a green variety of chalcedony, containing red inclusions of iron oxide that resemble drops of blood, giving heliotrope its alternative name of bloodstone. In a similar variety, the spots are yellow instead, known as plasma. Moss agate
What Is This Thing Called Love? (short story) What Is This Thing Called Love? (short story) "What Is This Thing Called Love?" is a science fiction short story by Isaac Asimov. The story was requested by Cele Goldsmith Lalli, editor of "Amazing Stories", as a satire of an article in "Playboy" called "Girls of the Slime God" which had suggested that pulp science fiction stories were concerned with aliens and sex. The story appeared in the March 1961 issue of "Amazing" as "Playboy and the Slime God", but Asimov later retitled it "What Is This Thing Called Love?" According to Asimov, in "1938-39 ... for some half a