Definition
Essexite which is also known as nepheline monzogabbro, is a dark gray or black holocrystalline plutonic Iigneous Rock
Trondhjemite is a leucocratic (light-colored) intrusive igneous rock. It is a variety of tonalite in which the plagioclase is mostly in the form of oligoclase. Trondhjemites are sometimes known as plagiogranites.
History
Origin
USA
Tonale, Italy
Discoverer
Unknown
Unknown
Etymology
From the locality in Essex County, Massachusetts,US
From Trondheim, Norway
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Hard Rock
Family
Group
Plutonic
Plutonic
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Granular
Phaneritic
Color
Dark Grey to Black
Black, Brown, Light to Dark Grey, White
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
✔
✘
✔
✘
Scratch Resistant
✔
✘
✔
✘
Stain Resistant
✔
✘
✔
✘
Wind Resistant
✔
✘
✔
✘
Acid Resistant
✔
✘
✔
✘
Appearance
Banded
Banded and Foilated
Architecture
Interior Uses
Decorative Aggregates, Homes, Interior Decoration
Decorative Aggregates, Entryways, Flooring, Homes, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
As Building Stone, As Facing Stone, 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
As Dimension Stone, Cement Manufacture, Cobblestones, Construction Aggregate, for Road Aggregate
Medical Industry
-
-
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
Artifacts, Monuments, Sculpture, Small Figurines
Other Uses
Commercial Uses
Cemetery Markers, Commemorative Tablets, Jewelry, Sea Defence, Tombstones
Cemetery Markers, Creating Artwork
Types
Intermediate volcanic rock
Intermediate intrusive rock
Features
Is one of the oldest rock, Smooth to touch
Is one of the oldest rock, Typically speckled black and white.
Archaeological Significance
Monuments
-
-
Famous Monuments
-
-
Sculpture
-
-
Famous Sculptures
-
-
Pictographs
-
-
Petroglyphs
-
-
Figurines
-
-
Fossils
Absent
Absent
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.
When alkali feldspar is extracted from granite, it changes to granitoid and later, it becomes trondhjemite with quartz as major mineral.
Composition
Mineral Content
Augite, Feldspar, Hornblende, Nepheline, Olivine, Plagioclase, Pyroxene
Albite, Amphibole, Apatite, Biotite, Feldspar, Hornblade, Ilmenite, Magnetite, Manganese Oxides, Olivine, Plagioclase, Pyroxene, Quartz, Sulfides, Titanite, Zircon
Compound Content
Aluminium Oxide, Ba, Ca, Cs, Potassium, Rb, Sodium, Sr
NaCl, CaO, MgO, Silicon Dioxide
Transformation
Metamorphism
✔
✘
✔
✘
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Impact Metamorphism, Regional Metamorphism
Weathering
✔
✘
✔
✘
Types of Weathering
Biological Weathering, Chemical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Erosion
✔
✘
✔
✘
Types of Erosion
Coastal Erosion, Glacier Erosion, Water Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
Physical Properties
Hardness
76-7
1
7
👆🏻
Grain Size
Fine Grained
Medium to Fine Coarse Grained
Fracture
Conchoidal
Conchoidal
Streak
Black
Bluish Black
Porosity
Highly Porous
Very Less Porous
Luster
-
Subvitreous to Dull
Compressive Strength
120.00 N/mm2130.00 N/mm2
0.15
450
👆🏻
Cleavage
-
-
Toughness
1.6
2.1
Specific Gravity
-99992.86-3
0
8.4
👆🏻
Transparency
Opaque
Opaque
Density
-9999 g/cm32.73 g/cm3
0
1400
👆🏻
Thermal Properties
Specific Heat Capacity
0.79 kJ/Kg K0.92 kJ/Kg K
0.14
3.2
👆🏻
Resistance
Impact Resistant, Pressure Resistant, Wear Resistant
Heat Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
India, Russia
-
Africa
South Africa
Egypt
Europe
Germany, Greece, Italy, Scotland, Turkey
Finland, Germany, Italy, Romania, Sweden, Turkey
Others
Greenland
-
Deposits in Western Continents
North America
Canada, USA
USA
South America
Brazil, Colombia, Venezuela
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru
Deposits in Oceania Continent
Australia
New Zealand, Queensland
New Zealand, South Australia, Western Australia