1.
basalt
A fine-grained, dark-colored volcanic rock formed from rapidly cooled lava. It is the most common rock on the Earth's surface and covers large areas of the ocean floor, as well as many volcanic regions in Japan. In everyday Japanese, the word appears mainly in geology, geography, and tourism contexts.
Composed of 玄武 (the Black Tortoise, one of the four mythological beasts associated with the north and the color black) and 岩 (rock). The name reflects the rock's characteristic dark, almost black color. The term was coined in the 19th century to translate the European geological term "basalt."
Usage
Primarily used in geology textbooks, science news, museum exhibits, and travel guides describing volcanic landscapes. Students encounter it in middle-school science class when learning about the classification of igneous rocks. It is not a word used in casual conversation, but most educated adults recognize it.
Common collocations
- 玄武岩の層: a layer of basalt
- 玄武岩でできている: to be made of basalt
- 玄武岩質の溶岩: basaltic lava
- 柱状節理の玄武岩: columnar-jointed basalt
- 海洋地殻を構成する玄武岩: basalt that makes up oceanic crust
Similar words
- 安山岩: andesite — another common volcanic rock, lighter in color than basalt and typical of Japan's land-based volcanoes
- 流紋岩: rhyolite — an even lighter-colored volcanic rock, higher in silica
- 花崗岩: granite — a plutonic (deep-formed) igneous rock; compositionally similar to rhyolite but coarser grained
- 溶岩: lava — the molten rock itself, which may solidify into basalt
- 火山岩: volcanic rock — the general category to which 玄武岩 belongs