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
Novaculite is a dense, hard, fine-grained, siliceous metamorpic rock which is a type of chert that breaks with conchoidal fracture
History
Origin
England
-
Discoverer
Abraham Gottlob Werner
Unknown
Etymology
From Old French esclate, from esclat (French éclat)
From Latin word novacula, for razor stone
Class
Metamorphic Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Hard Rock
Family
Group
-
-
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Foliated
Banded, Glassy, Rough, Vitreous
Color
Black, Brown, Buff, Green, Light to Dark Grey, Purple, Red, Shades of Blue
Black, Brown, Green, Grey, Red, White
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
✔
✘
✔
✘
Scratch Resistant
✔
✘
✔
✘
Stain Resistant
✔
✘
✔
✘
Wind Resistant
✔
✘
✔
✘
Acid Resistant
✔
✘
✔
✘
Appearance
Dull
Glassy or Pearly
Architecture
Interior Uses
Bathrooms, Decorative Aggregates, Entryways, Floor Tiles, Flooring, Homes, Hotels, Interior Decoration, Kitchens, Stair Treads
Countertops, Decorative Aggregates, Flooring, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
As Building Stone, Garden Decoration
Other Architectural Uses
Curbing
Curbing
Industry
Construction Industry
As Dimension Stone
Arrowheads, Building houses or walls, Cement Manufacture, Construction Aggregate, Cutting Tool, for Road Aggregate, Knives, Landscaping, Making natural cement, Production of Glass and Ceramics, Rail Track Ballast, Roadstone, Spear Points, Used to sharpen metal tools and weapons
Medical Industry
-
-
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
Artifacts, Monuments
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
Cemetery Markers, Gemstone, In aquifers, In fire-starting tools, Jewelry, Manufacture of tools, Pebbles are used in ball mills to grind in ceramics industry, To determine the gold content of jewelry
Types
Phyllite, Schist, and Slate
Sedimentary rock
Features
Easily splits into thin plates, Surfaces are often shiny, Very fine grained rock
Clasts are smooth to touch, Easily splits into thin plates, Has High structural resistance against erosion and climate
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.
Novaculite forms when microcrystals of silicon dioxide grow within soft sediments that become limestone or chalk. The formation of Novaculite can be either of chemical or biological origin.
Composition
Mineral Content
Apatite, Biotite, Chlorite, Feldspar, Graphite, Hematite, Kaolinite, Magnetite, Pyrite, Tourmaline, Zircon
Quartz, Silicon
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
Ca, Silicon Dioxide
Transformation
Metamorphism
✔
✘
✔
✘
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Regional Metamorphism
-
Weathering
✔
✘
✔
✘
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
-
Erosion
✔
✘
✔
✘
Types of Erosion
Coastal Erosion, Glacier Erosion, Water Erosion, Wind Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Physical Properties
Hardness
3-47
1
7
👆🏻
Grain Size
Very fine-grained
Fine Grained
Fracture
Splintery
Conchoidal
Streak
Light to dark brown
-
Porosity
Less Porous
Less Porous
Luster
Dull
Waxy and Dull
Compressive Strength
30.00 N/mm2450.00 N/mm2
0.15
450
👆🏻
Cleavage
Slaty
-
Toughness
1.2
1.5
Specific Gravity
2.65-2.82.5-2.7
0
8.4
👆🏻
Transparency
Opaque
Translucent to Opaque
Density
2.6-2.8 g/cm32.7 g/cm3
0
1400
👆🏻
Thermal Properties
Specific Heat Capacity
0.76 kJ/Kg K0.74 kJ/Kg K
0.14
3.2
👆🏻
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
China, India, Turkey
China, India, Iran, Japan, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam
Africa
-
Kenya, Morocco, South Africa, Tanzania
Europe
Belgium, France, Germany, Italy, Norway, Portugal, Spain, United Kingdom
Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom
Others
Arctic
Greenland, Mid-Atlantic Ridge
Deposits in Western Continents
North America
USA
Canada, Mexico, USA
South America
Brazil
Bolivia, Brazil
Deposits in Oceania Continent
Australia
-
New South Wales, Queensland, South Australia, Western Australia