Definition
Essexite which is also known as nepheline monzogabbro, is a dark gray or black holocrystalline plutonic Iigneous Rock
  
Coquina is a sedimentary rock that is composed either wholly or almost entirely of the transported, abraded, and mechanically-sorted fragments of the shells of molluscs, trilobites, brachiopods, or other invertebrates
  
History
  
  
Origin
USA
  
European Foreland Basins
  
Discoverer
Unknown
  
Unknown
  
Etymology
From the locality in Essex County, Massachusetts,US
  
From Concha (Latin)+ Coquina(Spanish) +conch(English)= Couquina (mid 19th century)
  
Class
Igneous Rocks
  
Sedimentary Rocks
  
Sub-Class
Durable Rock, Hard Rock
  
Durable Rock, Soft Rock
  
Family
  
  
Group
Plutonic
  
Not Applicable
  
Other Categories
Fine Grained Rock, Opaque Rock
  
Coarse Grained Rock, Opaque Rock
  
Texture
Granular
  
Clastic
  
Color
Dark Grey to Black
  
Beige, Buff, Orange
  
Maintenance
Less
  
More
  
Durability
Durable
  
Non-Durable
  
Water Resistant
Yes
  
No
  
Scratch Resistant
Yes
  
No
  
Stain Resistant
Yes
  
No
  
Wind Resistant
Yes
  
No
  
Acid Resistant
No
  
No
  
Appearance
Banded
  
Layered, Banded, Veined and Shiny
  
Architecture
  
  
Interior Uses
Decorative Aggregates, Homes, Interior Decoration
  
Decorative Aggregates, Homes, Hotels, Interior Decoration
  
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
  
Garden Decoration, Office Buildings
  
Other Architectural Uses
Curbing
  
Curbing
  
Industry
  
  
Construction Industry
As Dimension Stone, Building houses or walls, Cement Manufacture, Construction Aggregate, for Road Aggregate
  
Building houses or walls, Construction Aggregate
  
Medical Industry
Not Yet Used
  
Not Yet Used
  
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
  
Artifacts, Monuments, Sculpture, Small Figurines
  
Other Uses
  
  
Commercial Uses
Cemetery Markers, Commemorative Tablets, Jewelry, Sea Defence, Tombstones
  
Creating Artwork
  
Types
Not Available
  
Not Available
  
Features
Is one of the oldest rock, Smooth to touch
  
Available in Lots of Colors and Patterns, Is one of the oldest rock
  
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
Not Used
  
Used
  
Petroglyphs
Not Used
  
Used
  
Figurines
Used
  
Used
  
Fossils
Absent
  
Present
  
Formation
Essexite is a type of igneous rock, which is usually dark grey to black plutonic rock. For the formation of essexite, suitable magma with exact composition of K, Ba, Rb, Cs, Sr should be produced.
  
Coquina is a sedimentary rock which is formed when billions of small clam-like seashell, called Coquina, or cockleshell are die and hence are deposited, buried and turns into a rock when pressure is applied.
  
Composition
  
  
Mineral Content
Augite, Feldspar, Hornblende, Nepheline, Olivine, Plagioclase, Pyroxene
  
Apatite, Augite, Bronzite, Calcite, Chert, Chlorite, Clay Minerals, Epidote, Feldspar, Garnet, Micas, Muscovite or Illite
  
Compound Content
Aluminium Oxide, Ba, Ca, Cs, Potassium, Rb, Sodium, Sr
  
CaO, Carbon Dioxide, Iron(III) Oxide, MgO
  
Transformation
  
  
Metamorphism
Yes
  
No
  
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism
  
Not Applicable
  
Weathering
Yes
  
Yes
  
Types of Weathering
Biological Weathering, Chemical Weathering
  
Biological Weathering, Chemical Weathering, Mechanical Weathering
  
Erosion
Yes
  
Yes
  
Types of Erosion
Coastal Erosion, Glacier Erosion, Water Erosion
  
Coastal Erosion, Sea Erosion, Water Erosion, Wind Erosion
  
Physical Properties
  
  
Hardness
7
  
1-2
  
Grain Size
Fine Grained
  
Coarse Grained
  
Fracture
Conchoidal
  
Irregular
  
Streak
Black
  
White
  
Porosity
Highly Porous
  
Highly Porous
  
Luster
Not Available
  
Dull to Vitreous to Submetallic
  
Cleavage
Not Available
  
Not Available
  
Toughness
1.6
  
Not Available
  
Specific Gravity
Not Available
  
1.10-2.24
  
Transparency
Opaque
  
Opaque
  
Density
Not Available
  
2.8-2.9 g/cm3
  
Thermal Properties
  
  
Resistance
Impact Resistant, Pressure Resistant, Wear Resistant
  
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
  
Deposits in Eastern Continents
  
  
Asia
India, Russia
  
Not Yet Found
  
Africa
South Africa
  
Not Yet Found
  
Europe
Germany, Greece, Italy, Scotland, Turkey
  
United Kingdom
  
Others
Greenland
  
Not Yet Found
  
Deposits in Western Continents
  
  
North America
Canada, USA
  
USA
  
South America
Brazil, Colombia, Venezuela
  
Not Yet Found
  
Deposits in Oceania Continent
  
  
Australia
New Zealand, Queensland
  
Not Yet Found