(1) Piece of black, volcanic glass.

(2) Volcanic rock includes the volcanic glass obsidian.

(3) Trapped water was found in tiny volcanic glass beads returned to Earth in 1972 by the final manned mission to the moon, Apollo 17.

(4) A usually black or banded, hard volcanic glass that displays shiny, curved surfaces when fractured and is formed by rapid cooling of lava.

(5) In 2008(sentencedict .com), research of volcanic glass beads brought attention to the fact that there might be more water in the moon's interior than scientists had previously thought.

(6) The composition of volcanic glass gradually decreases Fe _ T , Mg and Ca with the increasing crystallinity.

(7) For example, many early human artifacts, such as arrowheads, are made of obsidian, a volcanic glass.

(8) When lava flows are erupted at the surface, they are necessarily rapidly chilled, and volcanic glasses are common.

(9) And if I did find the right one, I might never know it because I might overlook that black piece of volcanic glass, or, much more likely, Andy put it into his pocket and took it with him.

(10) A new type of chemical analysis has spotted the telltale signs of water molecules inside tiny beads of volcanic glass brought to Earth decades ago by the Apollo astronauts.

(11) Since glass has no sharp melting point, most types can be shaped while hot and plastic by many techniques, mostly blowing or molding. See also volcanic glass.

(12) The ledge was covered with heavy ash, called tephra, and speckled with droplets of volcanic glass and delicate lava threads known as Pele's hair.

(13) Smectite mainly came from the alteration of volcanic ash or volcanic glass and the weathering materials derived from land rocks.

(14) NATO took the threat seriously enough to limit military exercises after volcanic glass built up in fighter engines.

(15) But in 2008, an analysis of a handful of lunar volcanic glass beads suggested they might have formed in a watery environment.