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) with aliens and sex. According to Asimov the article was mostly based on "Marvel" since its contents had been the raciest. Cele Goldsmith Lalli, editor of "Amazing Stories", requested a satire of the "Playboy" article. Asimov set out to write a story telling how a sex-interested alien and humans might "really" interact. The story appeared in the March 1961 issue of "Amazing" as "Playboy and the Slime God", but when Asimov included it in his 1969 collection "Nightfall and Other Stories" he retitled it "What Is This Thing Called Love?" Goldsmith Lalli rewrote the story's last three paragraphs, a change