Definition
Variolites are a group of dark green basic igneous rocks which exhibit pale colored spots, or spherules, especially on weathered surfaces, that give them a pockmarked appearance
Mudstone is a fine-grained, dark gray sedimentary rock, which is formed from silt and clay and is similar to shale but has less laminations
History
Origin
France
-
Discoverer
Unknown
William Smith
Etymology
From Latin varius, speckled, variegated
From the English mud and stone, from low German mudde and stainaz
Class
Igneous Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Soft Rock
Family
Group
Volcanic
-
Other Categories
Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Glassy, Massive, Porphyritic, Scoriaceous, Vesicular
Clastic
Color
Black, Brown, Light to Dark Grey
Black, Blue, Brown, Green, Grey, Orange, Red, White, Yellow
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
✔
✘
✔
✘
Scratch Resistant
✔
✘
✔
✘
Stain Resistant
✔
✘
✔
✘
Wind Resistant
✔
✘
✔
✘
Acid Resistant
✔
✘
✔
✘
Appearance
Dull and Soft
Rough and Dull
Architecture
Interior Uses
Floor Tiles, Flooring, Homes, Hotels, Kitchens
Decorative Aggregates, Entryways, Floor Tiles, Interior Decoration
Exterior Uses
Garden Decoration, Office Buildings
As Building Stone, As Facing Stone, Paving Stone, Roof Tiles
Other Architectural Uses
Curbing
Curbing
Industry
Construction Industry
As Dimension Stone, Cobblestones, Rail Track Ballast, Roadstone
Cement Manufacture, Construction Aggregate, for Road Aggregate, Making natural cement, Raw material for the manufacture of mortar
Medical Industry
-
-
Antiquity Uses
Artifacts, Monuments, Sculpture
Sculpture, Small Figurines
Other Uses
Commercial Uses
Cemetery Markers, Creating Artwork
Creating Artwork, Pottery
Types
Metamorphic rock
Marl, Shale and Argillite
Features
Has High structural resistance against erosion and climate, Very fine grained rock
Available in Lots of Colors and Patterns, Smooth to touch, Very fine grained rock
Archaeological Significance
Monuments
-
-
Famous Monuments
-
-
Sculpture
-
-
Famous Sculptures
-
-
Pictographs
-
-
Petroglyphs
-
-
Figurines
-
-
Fossils
Absent
Present
Formation
Variolites are a group of dark green basic igneous rocks that exhibit pale colored spots on weathered surfaces that give them a pockmarked appearance.
Mudstone forms when very fine-grained clay particles are deposited in water which settle at the bottom of water bodies. They are buried and compacted by overlying sediment hence forming mudstone.
Composition
Mineral Content
Olivine, Plagioclase, Pyroxene
Biotite, Chlorite, Feldspar, Micas, Muscovite or Illite, Plagioclase, Pyrite, Quartz
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Aluminium Oxide, NaCl, CaO, Iron(III) Oxide, Silicon Dioxide
Transformation
Metamorphism
✔
✘
✔
✘
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
-
Weathering
✔
✘
✔
✘
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Chemical Weathering, Mechanical Weathering
Erosion
✔
✘
✔
✘
Types of Erosion
-
Chemical Erosion, Sea Erosion
Physical Properties
Hardness
62-3
1
7
👆🏻
Grain Size
-
Very fine-grained
Fracture
Conchoidal
-
Streak
White to Grey
White
Porosity
Less Porous
Highly Porous
Luster
-
Dull
Compressive Strength
37.50 N/mm225.00 N/mm2
0.15
450
👆🏻
Cleavage
-
Perfect
Toughness
2.3
2.6
Specific Gravity
2.8-32.2-2.8
0
8.4
👆🏻
Transparency
Opaque
Opaque
Density
2.9-3.1 g/cm32.4-2.8 g/cm3
0
1400
👆🏻
Thermal Properties
Specific Heat Capacity
0.84 kJ/Kg K0.39 kJ/Kg K
0.14
3.2
👆🏻
Resistance
Heat Resistant, Pressure Resistant, Wear Resistant
Heat Resistant, Impact Resistant
Deposits in Eastern Continents
Asia
India, Russia
Bangladesh, China, India, Russia
Africa
South Africa
Ethiopia, Kenya, Morocco, South Africa, Tanzania
Europe
Iceland
Austria, France, Germany, Greece, Italy, Romania, Scotland, Spain, Switzerland
Others
-
-
Deposits in Western Continents
North America
Canada, USA
USA
South America
Brazil
Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Deposits in Oceania Continent
Australia
-
New South Wales, New Zealand, Queensland, Victoria, Western Australia