Definition
Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism
Marl is an unconsolidated sedimentary rock consisting of clay and lime
History
Origin
England
-
Discoverer
Abraham Gottlob Werner
William Smith
Etymology
From Old French esclate, from esclat (French éclat)
From Old French marle, from Late Latin marglia
Class
Metamorphic Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Soft Rock
Family
Group
-
-
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Foliated
Earthy
Color
Black, Brown, Buff, Green, Light to Dark Grey, Purple, Red, Shades of Blue
Beige, Brown, Green, Grey, White
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
✔
✘
✔
✘
Scratch Resistant
✔
✘
✔
✘
Stain Resistant
✔
✘
✔
✘
Wind Resistant
✔
✘
✔
✘
Acid Resistant
✔
✘
✔
✘
Appearance
Dull
Rough and Dull
Architecture
Interior Uses
Bathrooms, Decorative Aggregates, Entryways, Floor Tiles, Flooring, Homes, Hotels, Interior Decoration, Kitchens, Stair Treads
Decorative Aggregates, Floor Tiles
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
As Building Stone, Roof Tiles
Other Architectural Uses
Curbing
Curbing
Industry
Construction Industry
As Dimension Stone
Cement Manufacture, Construction Aggregate, for Road Aggregate, Making natural cement, Raw material for the manufacture of mortar
Medical Industry
-
-
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
Artifacts, Jewellery, Sculpture, Small Figurines
Other Uses
Commercial Uses
Blackboards, Commemorative Tablets, Laboratory bench tops, Standard material for the bed of Billiard table, Standard material for the beds of Pool and Snooker table, Tombstones, Used in aquariums, Writing Slates
Creating Artwork, Soil Conditioner
Types
Phyllite, Schist, and Slate
Clay Marl ,Blue Marl, Red Marl, High Bank Marl, Shell Layer Marl, Under Shell Layer Marl, Sand Marl, Green Marl, Grey Marl and Clayey Marl
Features
Easily splits into thin plates, Surfaces are often shiny, Very fine grained rock
Generally rough to touch, Is one of the oldest rock, Splintery, Very fine grained rock
Archaeological Significance
Monuments
-
-
Famous Monuments
-
-
Sculpture
-
-
Famous Sculptures
-
-
Pictographs
-
-
Petroglyphs
-
-
Figurines
-
-
Fossils
Absent
Present
Formation
Slate is a low grade metamorphic rock that is generally formed by metamorphosis of mudstone or shale, under relatively low pressure and temperature conditions.
Marl forms when very fine-grained clay particles are deposited in water which settles at the bottom of water bodies and are compacted by overlying sediment; the water squeezes out and hence forming Marl rock.
Composition
Mineral Content
Apatite, Biotite, Chlorite, Feldspar, Graphite, Hematite, Kaolinite, Magnetite, Pyrite, Tourmaline, Zircon
Calcite, Clay, Dolomite, Gypsum, Micas, Pyrite, Quartz
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
Aluminium Oxide, NaCl, CaO, Iron(III) Oxide, Silicon Dioxide
Transformation
Metamorphism
✔
✘
✔
✘
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Regional Metamorphism
-
Weathering
✔
✘
✔
✘
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering
Erosion
✔
✘
✔
✘
Types of Erosion
Coastal Erosion, Glacier Erosion, Water Erosion, Wind Erosion
Chemical Erosion, Coastal Erosion, Water Erosion, Wind Erosion
Physical Properties
Hardness
3-42-3
1
7
👆🏻
Grain Size
Very fine-grained
Very fine-grained
Fracture
Splintery
Conchoidal
Streak
Light to dark brown
White
Porosity
Less Porous
Highly Porous
Luster
Dull
Dull
Compressive Strength
30.00 N/mm230.00 N/mm2
0.15
450
👆🏻
Cleavage
Slaty
-
Toughness
1.2
2.6
Specific Gravity
2.65-2.82.2-2.8
0
8.4
👆🏻
Transparency
Opaque
Opaque
Density
2.6-2.8 g/cm32.4-2.8 g/cm3
0
1400
👆🏻
Thermal Properties
Specific Heat Capacity
0.76 kJ/Kg K0.80 kJ/Kg K
0.14
3.2
👆🏻
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Heat Resistant, Impact Resistant
Deposits in Eastern Continents
Asia
China, India, Turkey
India, Pakistan, Russia
Africa
-
Ethiopia, Kenya, Morocco, South Africa
Europe
Belgium, France, Germany, Italy, Norway, Portugal, Spain, United Kingdom
Austria, France, Germany, Greece, Italy, Romania, Scotland, Spain, Switzerland
Others
Arctic
-
Deposits in Western Continents
North America
USA
USA
South America
Brazil
Colombia, Ecuador, Peru
Deposits in Oceania Continent
Australia
-
New South Wales, Victoria, Western Australia