MINERALOGY (GROUP 4)

solid materials with a highly ordered, microscopic structure, forming a crystal lattice that extends in all directions, and are known for their unique properties and uses

crystals

When molten rocks cools atoms and molecules slow down and begin to arrange themselves into a crystalline structure

Cooling of molten material

examples of cooling molten material

obsidian and basalt

When a liquid solution evaporates it leaves the dissolved substances

evaporation

examples of evaporation

sugar and table salt (halite)

When substance transition directly from a gas to a solid without passing through a liquid phase

sublimation

examples of sublimation

snowflakes

Crystals can form when hot, mineral-rich water cools and deposits minerals in cracks or cavities within rocks

hydrothermal process

examples of hydrothermal process

quartz and amethyst

Crystals can be grown in controlled laboratory environments using methods like the Czochralski process, flux growth, or vapor deposition.

artificial or laboratory growth

examples of artificial or laboratory growth

synthetic gemstones

refers to one of the many classes of crystals, space groups, and lattices. In crystallography terms, lattice system and crystal, the system are associated with each other with a slight difference.

crystal systems

It is the most unsymmetrical crystal system. All three axes are inclined towards each other, and they are of the same length. Based on the three inclined angles the various forms of crystals are in the paired faces.

triclinic system

It comprises three axes where two are at right angles to each other, and the third axis is inclined. All three axes are of different lengths. Based on the inner structure the monoclinic system includes Basal pinacoid and prisms with inclined end faces.

monoclinic system

it comprises three axes and is at right angles to each other. There are different lengths. Based on their Rhombic structure the orthorhombic system includes various crystal shapes namely pyramids, double pyramids, rhombic pyramids, and pinacoids.

orthorhombic system

Angles and axis in a trigonal system are similar to Hexagonal Systems. At the base of a hexagonal system (cross-section of a prism), there will be six sides while, in the trigonal system (base crosssection) there will be three sides.

trigonal system

It comprises four axes. The three axes are all contained within a single plane (called the basal plane) and are at 120°. They intersect each other at an angle of 60° The fourth axis intersects the other three axes at right angles.

hexagonal system

It consists of three axes. The main axis varies in length; it can either be short or long. The two-axis lie in the same plane and are of the same length.

tetragonal system

All three angles intersect at right angles and are of equal length. Crystal shapes of a cubic system based on inner structure (square) include octahedron, cube, and Hexaciscoherdron.

cubic system

refer to how a crystal interacts with light. These properties are crucial for understanding how crystals manipulate light, which is essential in various technological applications such as optics, photonics, and laser technology

optical properties

is related to the density of its atomic structure. Different refractive indices can cause phenomena like birefringence.

refractive index

: Some crystals exhibit ________, where they split light into two beams due to different refractive indices along different axes

birefringence

is an optical property of some minerals where a single light ray entering the mineral splits into two separate rays that travel at different speeds and exit at different angles. This occurs due to Double refraction, a phenomenon where light interacts with an anisotropic crystal structure.

birefrigence

he appearance or luster of a crystal can be metallic or non-metallic, depending on how it interacts with light

luster

Crystals often show anisotropic optical properties, meaning their optical behavior varies with direction. This can lead to effects like polarization

optical anisotropy

refer to how they react with other substances and their stability under different conditions. These properties are influenced by the type of chemical bonds holding the crystal together, such as ionic, covalent, metallic, or molecular bonds

chemical properties

a crystal determines its properties and behavior. Different compositions lead to different bonding types and strengths.

chemical composition

it is influenced by its surface properties and the density of atoms on its surface

reactivity

Crystals have varying _____ in different solvents, depending on their chemical structure and bonding

solubility

crystals are characteristics that can be observed without changing the chemical identity of the substance. These properties are influenced by the crystal's structure and bonding.

physical properties

Crystals have a repeating pattern of atoms, ions, or molecules, described by their unit cell and symmetry. This structure influences properties like cleavage and hardness

crystal structure and symmetry

Some crystals exhibit cleavage, which is the tendency to break along flat surfaces due to weaknesses in the crystal lattice.

cleavage

a crystal is related to its chemical bonding and atomic packing. Harder crystals have stronger bonds and more efficient

hardness

a crystal depends on the atomic packing factor (APF), which is the proportion of space filled by atoms in the unit cell.

density

The external shape of a crystal, influenced by its internal structure and growth conditions, is known as its ____.

habit

A mineral's hardness is a measure of its relative resistance to scratching, measured by scratching the mineral against another substance of known hardness on the _________.

mohs scale

concrete, glass and sand made of?

quartz

ceramics, and glass production made of?

feldspar

cement, limestone, and aggregate made of?

calcite

plaster and drywall made of?

gypsum

bricks and tiles made of?

clay minerals