pitchstone
Definition
- Noun:
- A type of volcanic glass: Pitchstone is a dark, usually black or dark green, natural glass formed by the rapid cooling of lava. It is similar to obsidian but has a dull, resinous or pitch-like luster, rather than a glassy shine, and often contains microscopic crystals.
Usage
- Pitchstone is a geological term used to describe a specific type of igneous rock. It is primarily used in academic, scientific, and geological contexts.
- Example:
Advanced Usage
- As a material: Historically, like obsidian, pitchstone could be fashioned into sharp tools or weapons by knapping due to its conchoidal fracture.
- Example: Archaeologists found pitchstone artifacts at the site, indicating trade from volcanic regions.
Variants and Related Words
- Obsidian (noun): A closely related volcanic glass that is typically black and has a bright, glassy luster, unlike the dull luster of pitchstone.
- Tachylite (noun): A basic (low-silica) volcanic glass, which is darker and heavier than the acidic (high-silica) pitchstone.
Synonyms
- Volcanic glass: The general category to which pitchstone belongs.
Different Meanings
- The word "pitchstone" does not have other common meanings outside of its specific geological definition. It is a compound noun formed from "pitch" (referring to its tar-like appearance) and "stone".
Noun
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dark acid granitic glass
