conchoidal

American  

[kong-koid-l] / kɒŋˈkɔɪd l /

adjective

Mineralogy.

1. noting a shell-like fracture form produced on certain minerals by a blow.

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conchoidal British  

/ kɒŋˈkɔɪdəl /

adjective

1. (of the fracture of minerals and rocks) having smooth shell-shaped convex and concave surfaces

2. (of minerals and rocks, such as flint) having such a fracture

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conchoidal Scientific  

/ kŏng-koid′l /

1. Of or relating to a mineral or rock surface that is characterized by smooth, shell-like curves. Obsidian and quartz often have conchoidal fractures.

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Other Word Forms

• subconchoidal
  adjective
• conchoidally
  adverb

Etymology

Origin of conchoidal

First recorded in 1660–70; conchoid + -al ¹

Example Sentences

See Examples For:

conchoidal

Mineral fracture surfaces may be rough, uneven, or show a conchoidal fracture.

From Textbooks ● Jan. 1, 2017

A conchoidal fracture has a smooth, curved surface like a shallow bowl or conch shell, often with curved ridges.

From Textbooks ● Jan. 1, 2017

At ordinary temperatures ebonite is hard and brittle and breaks with a well-marked conchoidal fracture.

From On Laboratory Arts by Threlfall, Richard

Their surfaces often show minute crescentic or rounded cracks which are the edges of small conchoidal fractures produced by the impact of one pebble on another during storms or floods.

From Encyclopaedia Britannica, 11th Edition, Volume 10, Slice 5 "Fleury, Claude" to "Foraker" by Various

It is opaque, of a reddish-brown colour, brittle, and has a smooth shining conchoidal fracture.

From The New Gresham Encyclopedia Volume 4, Part 1: Deposition to Eberswalde by Various