Scrabble Bingo of the Day: RHYOLITE

RHYOLITE  64 points (14 points without the bingo)

Definition: a volcanic rock [n]

Rhyolite is an igneous rock, which is one of the three main rock types, aside from sedimentary and metamorphic rock. It's also an extrusive volcanic rock, which is formed on the surface through the cooling and solidification of magma or lava from a volcano or fissure in the earth. But rhyolite is also designated as felsic because it's enriched in lighter elements, namely silicon dioxide.

Rhyolite has a composition very similar to plutonic granite, but has a much smaller grain size, and may have any texture, from glassy to aphanitic (mineral crystals invisible to the naked eye) to porphyritic (mineral crystals visible). Though rhyolite is much less common than granite, large amounts can be found in Yellowstone Park and in a quarry site in Adams County, Pennsylvania, which is listed on the National Register of Historic Places for its archaeological significance.

Inflections: RHYOLITES [pl.]

Similar Words: IGNEOUS, EXTRUSIVE, FISSURE(S), FELSIC, MAFIC, PLUTONIC, GRANITE(S), APHANITE(S), APHANITIC, PORPHYRITIC

 A folded rhyolite dyke mixed with gabbro (mafic rock, not felsic) on Mt. Sullivan, Antarctica.

Photo by euphro

 Natural Bridge in Yellowstone Park, made of rhyolite rock.

Photo by Judith Kirk

Lower Yellowstone Falls descend into a 590,000 year old canyon rhyolite lava flow.

Photo by The Likes Family

Chiricahua National Monument in Arizona, a forest of rock spires made of hardened rhyolite tuffs.

Photo by Ken Lund

So, just what is a Scrabble Bingo?

A bingo is when a player empties his or her rack in one turn, placing all seven of their letters on the board to create a word that's at least seven letters long. The term "bingo" is used primarily in the U.S., but elsewhere it's simply known as a "bonus" because you get a bonus of 50 points added to your turn's score. "Scrabble Bingo of the Day" will focus on these high scoring plays, teaching you some interesting and possibly unusual seven-letter or longer words accepted in a game of Scrabble.

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