Definition
Chalk is a soft, white, powdery limestone consisting mainly of fossil shells of foraminifers
Hornfels is a metamorphic rock formed by the contact between mudstone or other clay rich rock, and a hot igneous body, and represents a heat altered equivalent of the original rock
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 German which means hornstone
Class
Sedimentary Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Soft Rock
Durable Rock, Soft Rock
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Clastic or Non-Clastic
Granular, Platy
Color
Grey, White, Yellow
Brown, Dark Greenish - Grey, Green, Reddish Brown
Durability
Durable
Durable
Interior Uses
Decorative Aggregates, Homes, Interior Decoration
Decorative Aggregates, Flooring, Homes, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Paving Stone, Garden Decoration
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
Other Architectural Uses
Powder
Curbing
Construction Industry
As Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Aggregate, Making natural cement, raw material for manufacture of quicklime and slaked lime, Source of calcium
for Road Aggregate, Roadstone
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
Artifacts, Monuments
Commercial Uses
Alumina Refineries, Creating Artwork, Drawing on blackboards, Gymnasts, athletes and mountain climbers use for grip, In aquifers, Paper Industry, Production of Lime, Raw material for manufacture of quicklime, slaked lime, Soil Conditioner, Whiting, Whiting material in toothpaste, paint and paper
Cemetery Markers, Commemorative Tablets, Creating Artwork
Types
Chalk Marl and Marl
Biotite hornfels
Features
Clasts are smooth to touch, Is one of the oldest rock, Smooth to touch, Very fine grained rock
Smooth to touch
Archaeological Significance
Formation
Chalk is formed from lime mud, which accumulates on the sea floor which is then transformed into rock by geological processes.
Due to change in environmental conditions, rocks are heated and pressurized deep inside the Earth's surface. Hornfels is formed from the extreme heat caused by magma or by the intense collisions and friction of tectonic plates.
Mineral Content
Calcite, Clay, Clay Minerals, Quartz, Sand
Andalusite
Compound Content
Ca, NaCl, CaO
Fe, Mg
Types of Metamorphism
-
-
Types of Weathering
Biological Weathering, Chemical Weathering
Biological Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Water Erosion
Chemical Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
Grain Size
Very fine-grained
Fine Grained
Porosity
Highly Porous
Highly Porous
Specific Gravity
2.3-2.4
3.4-3.9
Transparency
Opaque
Opaque
Density
2.49-2.50 g/cm3
0.25-0.30 g/cm3
Resistance
Heat Resistant
Heat Resistant, Impact Resistant, Pressure Resistant
Deposits in Eastern Continents
Asia
Brunei, India, Indonesia, Malaysia, Singapore, Thailand, Vietnam
Bangladesh, Bhutan, China, India, North Korea, Qatar, Russia, Saudi Arabia, South Korea, Thailand
Africa
Cameroon, Chad, Ghana, Kenya, Malawi, Sudan, Tanzania, Togo, Zambia, Zimbabwe
Cameroon, East Africa, Tanzania, Western Africa
Europe
England, France, Germany, Spain, United Kingdom
United Kingdom
Deposits in Western Continents
North America
Canada, USA
Canada, USA
South America
Colombia
Bolivia, Brazil, Colombia, Ecuador
Deposits in Oceania Continent
Australia
Adelaide, New Zealand, Queensland, Victoria, Yorke Peninsula
New South Wales, New Zealand, Queensland, Western Australia
All about Chalk and Hornfels Properties
Know all about Chalk and Hornfels properties here. All properties of rocks are important as they define the type of rock and its application. Chalk belongs to Sedimentary Rocks while Hornfels belongs to Metamorphic Rocks.Texture of Chalk is Clastic or Non-Clastic whereas that of Hornfels is Granular, Platy. Chalk appears Soft and Hornfels appears Dull. The luster of Chalk is dull while that of Hornfels is shiny. Chalk is available in grey, white, yellow colors whereas Hornfels is available in brown, dark greenish - grey, green, reddish brown colors. The commercial uses of Chalk are alumina refineries, creating artwork, drawing on blackboards, gymnasts, athletes and mountain climbers use for grip, in aquifers, paper industry, production of lime, raw material for manufacture of quicklime, slaked lime, soil conditioner, whiting, whiting material in toothpaste, paint and paper and that of Hornfels are cemetery markers, commemorative tablets, creating artwork.