conchoidal

American  

[kong-koid-l] / kɒŋˈkɔɪd l /

adjective

Mineralogy.

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

---

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

---

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.

---

Other Word Forms

• conchoidally adverb
• subconchoidal adjective

Etymology

Origin of conchoidal

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

Example Sentences

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

Words flunked: dioceses, cantatrice, Nabuchodonosor, a fortiori, conchoidal.

From Time Magazine Archive

The wayleals formed arches and crowns, conchoidal convolutions, zones and wheels, hemispheres and globes, cones and pyramids.

From The Goddess of Atvatabar Being the history of the discovery of the interior world and conquest of Atvatabar by Bradshaw, William Richard

Farther up, the yellowish-white limestone which occurs in Slave Lake formed a great portion of them; but here a greenish-gray, and rather dark-coloured, compact limestone, with a flat conchoidal fracture, replaces it.

From Narrative of a Second Expedition to the Shores of the Polar Sea by Franklin, John