These unfamiliar words are from "Orphanage" by Robert Buettner (2004).

alidade: an indicator or a sighting apparatus on a plane table, used in angular measurement

astrobleme: a scar on the earth's surface left from the impact of a meteorite

balalaika: a Russian instrument with a triangular body and three strings that produces sounds like those of a mandolin

rhyolite: a fine-grained extrusive volcanic rock, similar to granite in composition and usually exhibiting flow lines

salient: the area of a military defense, such as a battle line, that projects closest to the enemy

sear: the catch in a gunlock that keeps the hammer halfcocked or fully cocked

Jon

About to start: "More than Human" by Theodore Sturgeon (1952)