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

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

From Textbooks ● Jan. 1, 2017

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

From Textbooks ● Jan. 1, 2017

The fracture is perfectly conchoidal, so that blows with a hammer detach flakes which have convex, slightly undulating surfaces.

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

The fracture of this stone has in all instances been found to be irregularly conchoidal, and on exposure to the atmosphere and subjection to fire it crumbled to pieces.

From The History of Louisville, from the Earliest Settlement till the Year 1852 by Casseday, Ben

The purest flints have the most perfect conchoidal fracture, and prehistoric man is known to have quarried or mined certain bands of flint which were specially suitable for his purposes.

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