Greywacke

Rarity: Uncommon

A topic a little better known than average, read and translated beyond its own country.

Rarity follows how well known the article is: its views on the French and English Wikipedia over a year, and the number of languages it exists in.

At a glance

Class

Notion

Domain

Science and technology

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What Wikipedia says

Greywacke or graywacke (German: Grauwacke 'a grey, earthy rock') is a variety of sandstone generally characterized by its hardness (6–7 on Mohs scale), dark color, and poorly sorted angular grains of quartz, feldspar, and small rock fragments or sand-size lithic fragments set in a compact, clay-fine matrix.

Excerpt from the Wikipedia article “Greywacke”, under the CC BY-SA 4.0 license. Read the article on Wikipedia

Image: www.mineraly.sk, CC BY 2.0, via Wikimedia Commons.