Definition
Chalk is a soft, white, powdery limestone consisting mainly of fossil shells of foraminifers
Picrite is a variety of high-magnesium olivine basalt that is very rich in the mineral olivine
History
Origin
-
Hawaii Islands
Discoverer
Unknown
Unknown
Etymology
From old English cealc chalk, lime, plaster; pebble, from Greek khalix small pebble, in English transferred to the opaque, white, soft limestone
From Greek pikros bitter + -ite, 19th century
Class
Sedimentary Rocks
Igneous Rocks
Sub-Class
Durable Rock, Soft Rock
Durable Rock, Hard Rock
Family
Group
-
Volcanic
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock