GEOLOGY AND ROCK SYSTEM

Minerals are naturally occurring, inorganic substances with a specific chemical composition and a crystalline structure. They are the building blocks of rocks and form the Earth's crust. Here are some key characteristics and information about minerals:

• Naturally Occurring: Minerals are formed through natural geological processes and are not manufactured by humans. They can be found in the Earth's crust, and some are also found in the Earth's mantle.

• Inorganic: Minerals are not derived from living organisms. While some substances found in nature might seem similar to minerals, such as coal or amber, they are not classified as minerals because they originate from organic processes.

• Solid State: Minerals are typically solid at room temperature, although exceptions exist. For example, mercury is a mineral but is liquid at room temperature.

• Definite Chemical Composition: Minerals have a specific chemical formula that defines their composition. Each mineral is composed of certain elements in fixed proportions. For example, quartz (SiO2) consists of silicon and oxygen in a 1:2 ratio.

• Crystalline Structure: Minerals have a repeating internal arrangement of atoms or ions, forming a crystalline structure. This structure gives minerals their characteristic geometric shapes and cleavage patterns.

• Distinctive Physical Properties:

  • Color: The color of a mineral can vary, but it is not always a reliable characteristic for identification.
  • Luster: The way a mineral reflects light (e.g., metallic, vitreous, pearly).
  • Hardness: The resistance of a mineral to scratching. Measured on the Mohs scale.
  • Cleavage and Fracture: Cleavage refers to how a mineral breaks along planes of weakness, and fracture refers to how it breaks irregularly.
  • Streak: The color of a mineral's powder when scratched on a streak plate.

• Common Minerals:

  • Quartz: Composed of silicon and oxygen, quartz is one of the most abundant minerals in the Earth's crust.
  • Feldspar: A group of minerals that are the most abundant group in the Earth's crust.
  • Mica: Known for its perfect cleavage into thin sheets.
  • Calcite: A common mineral with a carbonate composition.
  • Halite: Composed of sodium and chlorine, halite is commonly known as table salt.

The Earth's crust is primarily composed of various elements, with a few key elements making up the majority of its composition. These major elements, often referred to as the "rock-forming elements," are essential components of common minerals found in the Earth's crust. The major elements and their approximate percentage composition in the Earth's crust are as follows:

• Oxygen (O): Oxygen is the most abundant element in the Earth's crust, constituting about 46.6% of the Earth's crust by weight. It is a key component of silicate minerals, such as quartz and feldspar.

• Silicon (Si): Silicon is the second most abundant element in the Earth's crust, making up approximately 27.7% of the crust. It is a major component of silicate minerals and is often combined with oxygen to form silicon dioxide (SiO2), a common mineral known as quartz.

• Aluminum (Al): Aluminum is the third most abundant element in the Earth's crust, comprising about 8.23%. It is a significant component of minerals like feldspar and bauxite.

• Iron (Fe): Iron is present in the Earth's crust at around 5.0%. It is a crucial element in minerals such as olivine, pyroxene, and various iron oxides like magnetite and hematite.

• Calcium (Ca): Calcium makes up about 3.6% of the Earth's crust and is found in minerals like calcite and dolomite. It is essential for the formation of carbonate minerals.

• Sodium (Na): Sodium constitutes about 2.8% of the Earth's crust and is found in minerals like feldspar and sodalite.

• Potassium (K): Potassium makes up approximately 2.6% of the Earth's crust and is a significant component of minerals like feldspar and muscovite.

• Magnesium (Mg): Magnesium is present at about 2.1% in the Earth's crust and is a major component of minerals such as olivine and pyroxene

 

Element	Abundance (weight %)	Properties	Examples of Minerals
Oxygen (O)	46.6	Highly reactive, forms oxides	Quartz, Feldspar, Mica
Silicon (Si)	27.7	Forms strong Si-O bonds	Quartz, Feldspar, Clay minerals
Aluminum (Al)	8.13	Light, corrosion-resistant	Feldspar, Clay minerals, Bauxite
Iron (Fe)	5.00	Malleable, ductile, ferromagnetic	Hematite, Magnetite, Pyrite
Calcium (Ca)	3.63	Essential for life, forms strong bonds	Calcite, Gypsum, Dolomite
Sodium (Na)	2.83	Highly reactive, forms salts	Halite (Rock salt), Feldspar
Potassium (K)	2.60	Essential for life, forms salts	Feldspar, Mica, Sylvite
Magnesium (Mg)	2.08	Lightweight, strong	Dolomite, Magnesite, Olivine
Titanium (Ti)	0.44	Strong, corrosion-resistant	Rutile, Ilmenite, Titanite
Hydrogen (H)	0.14	Highly reactive, forms water	Water, Clay minerals
Other elements	~1.45	Vary in abundance and properties	Phosphorus, Manganese, Sulfur, Carbon, Chlorine

 

 

 

Minerals – Feldspar, Quartz, Pyroxene Amphibole, Mica , Olivine

 

 

Mineral	Composition	Appearance	Common Uses
Feldspar	(K,Na,Ca)(Al,Si)₃O₈	White, pink, gray, brown crystals	Ceramics, glass production, igneous rocks
Quartz	SiO₂	Clear, colorless crystals	Glassmaking, electronics, jewelry
Pyroxene	XY(Si,Al)₂O₆ (X=Ca,Na,Fe; Y=Mg,Fe,Al)	Dark green to black crystals	Basalt, metamorphic rocks
Amphibole	Complex compositions including Na, Ca, Fe, Mg	Dark green, black, brown crystals	Basalt, metamorphic rocks
Mica	Sheet silicate minerals (e.g., muscovite)	Thin, transparent, pearly luster	Cosmetics, electronics, construction materials
Olivine	(Mg,Fe)₂SiO₄	Green crystals	Peridot gemstone, refractory materials

 

 

 

 

Physical Characteristics–Crystal Form, Cleavage Fracture, Lusture, Color, Streak Transparency, Structure, Hardness, Specific Gravity

 

 

Mineral	Crystal Form	Cleavage/Fracture	Lustre	Color	Streak	Transparency	Structure	Hardness	Specific Gravity
Quartz	Hexagonal prisms	Conchoidal fracture	Vitreous	Clear, various	White	Transparent	Crystalline	7	2.65
Mica	Sheet-like	Perfect basal	Pearly	Various	White	Transparent	Crystalline	2.5-3.5	2.8-3.0
Pyroxene	Short prismatic	Cleavage at angles	Vitreous	Dark green to black	White to gray	Transparent	Crystalline	5-7	3.2-3.6
Amphibole	Prismatic or blocky	Perfect cleavage	Vitreous	Dark green to black	White to gray	Transparent	Crystalline	5-6	2.9-3.6
Feldspar	Blocky or tabular	Two directions	Vitreous	White, pink, brown	White	Transparent	Crystalline	6	2.5-2.8
Olivine	Granular, elongated	Conchoidal fracture	Vitreous	Green to yellow	White	Transparent	Crystalline	6.5-7	3.2-4.4

 

 

Metallic minerals

 

Metallic minerals are minerals that contain metals, and they can be categorized into two main types: ferrous and non-ferrous. The classification is based on whether the minerals contain iron (ferrous) or not (non-ferrous). Additionally, some metallic minerals are considered precious due to their rarity and high economic value

 

Two types of Metallic Minerals:

 

1.Ferrous Metallic Minerals

2.Non-Ferrous Metallic Minerals

 

Metallic Minerals	Type	Composition and Examples	Main Uses
Gold	Precious	Native gold, gold nuggets	Jewelry, electronics, investment
Silver	Precious	Native silver, argentite, chlorargyrite	Jewelry, electronics, photography
Platinum	Precious	Native platinum, sperrylite	Catalytic converters, jewelry
Palladium	Precious	Pd-native, palladinite	Catalytic converters, electronics
Iron Ore	Ferrous	Hematite, magnetite, siderite	Steel production, construction
Copper Ore	Non-Ferrous	Chalcopyrite, bornite, malachite	Wiring, plumbing, electronics
Zinc Ore	Non-Ferrous	Sphalerite	Galvanization, alloys, batteries
Lead Ore	Non-Ferrous	Galena	Batteries, radiation shielding, construction
Tin Ore	Non-Ferrous	Cassiterite	Solder, tinplate, alloys
Aluminum Ore	Non-Ferrous	Bauxite	Aluminum production, construction
Nickel Ore	Non-Ferrous	Pentlandite, garnierite	Stainless steel, batteries, aerospace
Tungsten Ore	Non-Ferrous	Scheelite, wolframite	Hard alloys, high-speed tools
Cobalt Ore	Non-Ferrous	Cobaltite, skutterudite	Batteries, magnetic materials, aerospace alloys
Manganese Ore	Non-Ferrous	Pyrolusite, rhodochrosite	Steel production, batteries
Chromium Ore	Non-Ferrous	Chromite	Stainless steel, chrome plating

 

 

Non-metallic Minerals

 

Non-metallic minerals are minerals that lack metal elements in their chemical composition. They are often used in various industrial applications and include a wide range of minerals. 

 

Non-Metallic Minerals	Composition/Formula	Appearance	Common Uses
Sulphur	Chemical Formula: S₈	Yellow, brittle solid	- Production of sulfuric acid - Vulcanization of rubber - Manufacturing of fertilizers
Phosphates	Chemical Formula: PO₄³⁻	Various forms	- Major component of fertilizers - Food industry additives - Detergents and cleaning agents
Cement	Main Components: Limestone, Clay, Shale, Silica Sand	Fine powder before mixing with water; solid after setting	- Essential in concrete production - Construction of buildings, roads, bridges, etc. - Binding agent in various applications

 

 

 

DIfferences between Metallic and Non Metallic Minerals

 

Characteristic	Metallic Minerals	Non-Metallic Minerals
Composition	Contain metals in their chemical structure.	Lack metal elements in their chemical structure.
Examples	Iron ore (hematite, magnetite), copper ore (chalcopyrite), gold, silver.	Quartz, gypsum, limestone, sulfur.
Luster	Often exhibit metallic luster (shiny appearance).	Exhibit non-metallic luster (vitreous, pearly, dull, etc.).
Conductivity	Conduct electricity and heat.	Typically do not conduct electricity or heat.
Malleability and Ductility	Can be hammered into thin sheets (malleability) and drawn into thin wires (ductility).	Generally lack malleability and ductility.
Density	Generally higher density.	Tend to have lower density.
Uses	Used in various industries including construction, transportation, electronics, and manufacturing.	Used in various industries such as construction, agriculture, chemicals, and manufacturing.
Abundance	Some are abundant, while others are relatively rare.	Often more abundant and widespread.
Economic Value	Many have high economic value, especially those used in the production of metals.	Economic value varies; some are valued for industrial applications.
Processing	Often require extensive processing to extract and refine the metals.	Processing methods vary but may involve crushing, grinding, and chemical treatment.