obsidian

«obsidian» in Mova's school dictionary: a hard, shiny black (or dark) natural glass that forms… — its meaning for a pupil, its sense in the lessons and examples, with 4 sentences of Mova's corpora that use it.

part of speech

noun (obsidian; uncountable)

meaning for a pupil

1) Obsidian is a hard, shiny black (or dark) natural glass that forms when lava from a volcano cools very quickly. tree →

2) Obsidian was used long ago to make very sharp knives, arrowheads and mirrors. tree →

sense in the lessons

In science lessons on rocks, obsidian is an igneous rock (made from cooled lava) that cooled too fast for crystals to grow, so it is glassy; when it breaks it has very sharp curved edges. In history, the Aztecs and other peoples made tools and mirrors from it. In the game Minecraft, obsidian is a very hard block. Phrases: «obsidian blade», «volcanic glass».

examples

• Obsidian is black volcanic glass. tree →
• Obsidian forms when lava cools very quickly. tree →
• Ancient people made sharp arrowheads from obsidian. tree →
• The museum had an Aztec mirror made of obsidian. tree →
• In Minecraft you need obsidian to build a portal. tree →
• Obsidian is an igneous rock. tree →

note

Uncountable: «a piece of obsidian». Pronounced ob-SID-ee-un. Safety: broken obsidian is sharper than a knife, so handle with care.

In the corpora

• Lightning striking sand can melt it into glass tubes called fulgurites; volcanoes make a natural black glass called obsidian.
• Obsidian is natural glass that forms when lava cools so fast that no crystals can grow.
• Sharp volcanic glass called obsidian travelled hundreds of kilometres over 10,000 years ago.
• Obsidian, a sharp volcanic glass, was traded over long distances more than 10,000 years ago, before the first cities.

Trees and pragmatics

Every meaning and example of «obsidian» parsed by Mova, each sentence with its dependency tree and frames.