Definition
Marl is an unconsolidated sedimentary rock consisting of clay and lime
  
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
  
History
  
  
Origin
Unknown
  
New Zealand
  
Discoverer
Unknown
  
Unknown
  
Etymology
From Old French marle, from Late Latin marglia
  
From German which means hornstone
  
Class
Sedimentary Rocks
  
Metamorphic Rocks
  
Sub-Class
Durable Rock, Soft Rock
  
Durable Rock, Soft Rock
  
Family
  
  
Group
Not Applicable
  
Not Applicable
  
Other Categories
Fine Grained Rock, Opaque Rock
  
Fine Grained Rock, Opaque Rock
  
Texture
Earthy
  
Granular, Platy
  
Color
Beige, Brown, Green, Grey, White
  
Brown, Dark Greenish - Grey, Green, Reddish Brown
  
Maintenance
Less
  
Less
  
Durability
Durable
  
Durable
  
Water Resistant
Yes
  
Yes
  
Scratch Resistant
No
  
No
  
Stain Resistant
No
  
No
  
Wind Resistant
No
  
No
  
Acid Resistant
No
  
No
  
Appearance
Rough and Dull
  
Dull
  
Architecture
  
  
Interior Uses
Decorative Aggregates, Floor Tiles
  
Decorative Aggregates, Flooring, Homes, Interior Decoration
  
Exterior Uses
As Building Stone, Roof Tiles
  
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
  
Other Architectural Uses
Curbing
  
Curbing
  
Industry
  
  
Construction Industry
Cement Manufacture, Construction Aggregate, for Road Aggregate, Making natural cement, Raw material for the manufacture of mortar
  
for Road Aggregate, Roadstone
  
Medical Industry
Not Yet Used
  
Not Yet Used
  
Antiquity Uses
Artifacts, Jewellery, Sculpture, Small Figurines
  
Artifacts, Monuments
  
Other Uses
  
  
Commercial Uses
Creating Artwork, Soil Conditioner
  
Cemetery Markers, Commemorative Tablets, Creating Artwork
  
Types
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
  
Biotite hornfels
  
Features
Generally rough to touch, Is one of the oldest rock, Splintery, Very fine grained rock
  
Smooth to touch
  
Archaeological Significance
  
  
Monuments
Not Yet Used
  
Used
  
Famous Monuments
Not Applicable
  
Data Not Available
  
Sculpture
Used
  
Not Yet Used
  
Famous Sculptures
Data Not Available
  
Not Applicable
  
Pictographs
Used
  
Used
  
Petroglyphs
Used
  
Used
  
Figurines
Used
  
Not Yet Used
  
Fossils
Present
  
Absent
  
Formation
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.
  
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.
  
Composition
  
  
Mineral Content
Calcite, Clay, Dolomite, Gypsum, Micas, Pyrite, Quartz
  
Andalusite
  
Compound Content
Aluminium Oxide, NaCl, CaO, Iron(III) Oxide, Silicon Dioxide
  
Fe, Mg
  
Transformation
  
  
Metamorphism
No
  
No
  
Types of Metamorphism
Not Applicable
  
Not Applicable
  
Weathering
Yes
  
Yes
  
Types of Weathering
Biological Weathering, Chemical Weathering
  
Biological Weathering
  
Erosion
Yes
  
Yes
  
Types of Erosion
Chemical Erosion, Coastal Erosion, Water Erosion, Wind Erosion
  
Chemical Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
  
Physical Properties
  
  
Hardness
2-3
  
2-3
  
Grain Size
Very fine-grained
  
Fine Grained
  
Fracture
Conchoidal
  
Conchoidal
  
Streak
White
  
Unknown
  
Porosity
Highly Porous
  
Highly Porous
  
Luster
Dull
  
Shiny
  
Compressive Strength
Not Available
  
Cleavage
Not Available
  
Perfect
  
Toughness
2.6
  
Not Yet Found
  
Specific Gravity
2.2-2.8
  
3.4-3.9
  
Transparency
Opaque
  
Opaque
  
Density
2.4-2.8 g/cm3
  
0.25-0.30 g/cm3
  
Thermal Properties
  
  
Specific Heat Capacity
Not Available
  
0.84 kJ/Kg K
  
15
Resistance
Heat Resistant, Impact Resistant
  
Heat Resistant, Impact Resistant, Pressure Resistant
  
Deposits in Eastern Continents
  
  
Asia
India, Pakistan, Russia
  
Bangladesh, Bhutan, China, India, North Korea, Qatar, Russia, Saudi Arabia, South Korea, Thailand
  
Africa
Ethiopia, Kenya, Morocco, South Africa
  
Cameroon, East Africa, Tanzania, Western Africa
  
Europe
Austria, France, Germany, Greece, Italy, Romania, Scotland, Spain, Switzerland
  
United Kingdom
  
Others
Not Yet Found
  
Not Yet Found
  
Deposits in Western Continents
  
  
North America
USA
  
Canada, USA
  
South America
Colombia, Ecuador, Peru
  
Bolivia, Brazil, Colombia, Ecuador
  
Deposits in Oceania Continent
  
  
Australia
New South Wales, Victoria, Western Australia
  
New South Wales, New Zealand, Queensland, Western Australia