Definition
Chalk is a soft, white, powdery limestone consisting mainly of fossil shells of foraminifers
Gabbro is an intrusive igneous rock which is chemically equivalent to plutonic Basalt
History
Origin
-
Germany
Discoverer
Unknown
Christian Leopold von Buch
Etymology
From old English cealc chalk, lime, plaster; pebble, from Greek khalix small pebble, in English transferred to the opaque, white, soft limestone
From Latin glaber bare, smooth, bald
Class
Sedimentary Rocks
Igneous Rocks
Sub-Class
Durable Rock, Soft Rock
Durable Rock, Hard Rock
Family
Group
-
Plutonic
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Opaque Rock