rhyolite
rhyolite — noun
1. A light-coloured volcanic rock, often grey, pink, or pale brown, that forms when
A light-coloured volcanic rock, often grey, pink, or pale brown, that forms when thick, slow-moving lava — rich in silica, the same mineral found in sand and glass — cools and hardens on the Earth's surface.
Pale grey hills near the village are made of rhyolite, a light fine-grained rock.
uncountable noun for general reference
Dr. Okafor collected pinkish-grey rhyolite with a fine grain, showing fast surface cooling.
The pink stone in the wall is rhyolite, with wavy bands from thick lava flow.
When the volcano erupted, thick rhyolite lava flowed slowly down the slope and then hardened.
Geologists study rhyolite's light colour and fine grain to find old surface lava flows.
- volcanic rock
broader category that includes rhyolite, basalt, andesite, and many others
- felsite
a general term for light-coloured volcanic rocks; rhyolite is a specific type of felsite
- basalt
dark-coloured volcanic rock with low silica content, opposite end of the silica scale from rhyolite
文法句型
rhyolite as an uncountable mass noun
a rhyolite (a particular type or sample)
用法筆記
Frequently used as an uncountable noun when referring to the rock in general (e.g. 'Rhyolite is common in this area'). Countable use ('a rhyolite') is possible when referring to a particular sample or variety. In geology, 'acid' in descriptions of rhyolite refers to high silica content, not chemical acidity.