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
Unknown
  
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
Not Applicable
  
Volcanic
  
Other Categories
Fine Grained Rock, Opaque Rock
  
Fine Grained Rock, Opaque Rock
  
Texture
Clastic or Non-Clastic
  
Earthy, Rough
  
Color
Grey, White, Yellow
  
Black, Brown, Colourless, Green, Grey, Pink, White, Yellow
  
Maintenance
Less
  
Less
  
Durability
Durable
  
Durable
  
Water Resistant
No
  
Yes
  
Scratch Resistant
No
  
Yes
  
Stain Resistant
No
  
Yes
  
Wind Resistant
No
  
Yes
  
Acid Resistant
No
  
Yes
  
Appearance
Soft
  
Rough and Shiny
  
Architecture
  
  
Interior Uses
Decorative Aggregates, Homes, Interior Decoration
  
Countertops, Decorative Aggregates, Homes, Interior Decoration
  
Exterior Uses
As Building Stone, As Facing Stone, Paving Stone, Garden Decoration
  
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
  
Other Architectural Uses
Powder
  
Curbing
  
Industry
  
  
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
  
As a Sintering Agent in Steel Industry to process Iron Ore, Cement Manufacture, for Road Aggregate, Manufacture of Magnesium and Dolomite Refractories, Roadstone, Used for flooring, stair treads, borders and window sills.
  
Medical Industry
Not Yet Used
  
Not Yet Used
  
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
  
Artifacts, Monuments, Sculpture
  
Other Uses
  
  
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
  
As a Feed Additive for Livestock, As armour rock for sea walls, Metallurgical Flux, Pottery, Source of Magnesia (MgO)
  
Types
Not Available
  
Oceanite
  
Features
Clasts are smooth to touch, Is one of the oldest rock, Smooth to touch, Very fine grained rock
  
Host Rock for Lead
  
Archaeological Significance
  
  
Monuments
Used
  
Used
  
Famous Monuments
Data Not Available
  
Data Not Available
  
Sculpture
Used
  
Used
  
Famous Sculptures
Data Not Available
  
Data Not Available
  
Pictographs
Used
  
Not Used
  
Petroglyphs
Used
  
Not Used
  
Figurines
Used
  
Used
  
Fossils
Present
  
Absent
  
Formation
Chalk is formed from lime mud, which accumulates on the sea floor which is then transformed into rock by geological processes.
  
Picrite is a fine-grained, hard rock which is a type of metasomatite, essentially altered basalt. It forms with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.
  
Composition
  
  
Mineral Content
Calcite, Clay, Clay Minerals, Quartz, Sand
  
Biotite, Olivine, Plagioclase, Pyrrhotite
  
Compound Content
Ca, NaCl, CaO
  
Al, CaO, Carbon Dioxide, Mg, MgO
  
Transformation
  
  
Metamorphism
No
  
Yes
  
Types of Metamorphism
Not Applicable
  
Burial Metamorphism, Cataclastic Metamorphism, Impact Metamorphism, Regional Metamorphism
  
Weathering
Yes
  
Yes
  
Types of Weathering
Biological Weathering, Chemical Weathering
  
Biological Weathering
  
Erosion
Yes
  
Yes
  
Types of Erosion
Chemical Erosion, Coastal Erosion, Water Erosion
  
Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
  
Physical Properties
  
  
Hardness
1
  
6.8
  
Grain Size
Very fine-grained
  
Fine Grained
  
Fracture
Not Available
  
Uneven
  
Streak
White
  
White, Greenish White or Grey
  
Porosity
Highly Porous
  
Less Porous
  
Luster
Dull
  
Subvitreous to Dull
  
Compressive Strength
Not Available
  
189.00 N/mm
2
  
11
Cleavage
Non-Existent
  
Imperfect
  
Toughness
1
  
2.1
  
Specific Gravity
2.3-2.4
  
2.75-2.92
  
Transparency
Opaque
  
Opaque
  
Density
2.49-2.50 g/cm3
  
1.5-2.5 g/cm3
  
Thermal Properties
  
  
Specific Heat Capacity
0.90 kJ/Kg K
  
12
0.88 kJ/Kg K
  
13
Resistance
Heat Resistant
  
Heat Resistant
  
Deposits in Eastern Continents
  
  
Asia
Brunei, India, Indonesia, Malaysia, Singapore, Thailand, Vietnam
  
India, Russia
  
Africa
Cameroon, Chad, Ghana, Kenya, Malawi, Sudan, Tanzania, Togo, Zambia, Zimbabwe
  
South Africa
  
Europe
England, France, Germany, Spain, United Kingdom
  
Iceland
  
Others
Not Yet Found
  
Not Yet Found
  
Deposits in Western Continents
  
  
North America
Canada, USA
  
Canada, USA
  
South America
Colombia
  
Brazil
  
Deposits in Oceania Continent
  
  
Australia
Adelaide, New Zealand, Queensland, Tonga, Victoria, Yorke Peninsula
  
Not Yet Found
  
Chalk vs Picrite Characteristics
Though some rocks look identical, they have certain characteristics which distinguish them from others. Characteristics of rocks include texture, appearance, color, fracture, streak, hardness etc. Chalk vs Picrite characteristics assist us to distinguish and recognize rocks. Also you can check about Properties of Chalk and Properties of Picrite. Learn more about Chalk vs Picrite in the next section. The interior uses of Chalk include Decorative aggregates, Homes and Interior decoration whereas the interior uses of Picrite include Countertops, Decorative aggregates, Homes and Interior decoration. Due to some exceptional properties of Chalk and Picrite, they have various applications in construction industry. The uses of Chalk in construction industry include 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 and that of Picrite include As a sintering agent in steel industry to process iron ore, Cement manufacture, For road aggregate, Manufacture of magnesium and dolomite refractories, Roadstone, Used for flooring, stair treads, borders and window sills..
More about Chalk and Picrite
Here you can know more about Chalk and Picrite. The life cycle of a rock consists of formation of rock, composition of rock and transformation of rock. The composition of Chalk and Picrite consists of mineral content and compound content. The mineral content of Chalk includes Calcite, Clay, Clay Minerals, Quartz, Sand and mineral content of Picrite includes Biotite, Olivine, Plagioclase, Pyrrhotite. You can also check out the list of all Sedimentary Rocks. When we have to compare Chalk vs Picrite, the texture, color and appearance plays an important role in determining the type of rock. Chalk is available in grey, white, yellow colors whereas, Picrite is available in black, brown, colourless, green, grey, pink, white, yellow colors. Appearance of Chalk is Soft and that of Picrite is Rough and Shiny. Properties of rock is another aspect for Chalk vs Picrite. The hardness of Chalk is 1 and that of Picrite is 6.8. The types of Chalk are Not Available whereas types of Picrite are Oceanite. Streak of rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Chalk is white while that of Picrite is white, greenish white or grey. The specific heat capacity of Chalk is 0.90 kJ/Kg K and that of Picrite is 0.88 kJ/Kg K. Depending on the properties like hardness, toughness, specific heat capacity, porosity etc., rocks are resistant to heat, wear, impact, etc.Chalk is heat resistant whereas Picrite is heat resistant.