Crystal Structure and Properties
- Crystals are solids with a highly ordered microscopic structure.
- Polycrystals are composed of many microscopic crystals.
- Amorphous solids, like glass, have no periodic arrangement.
- Crystallization is the process of crystal formation.
- Lead crystal and crystal glass are actually types of glass, not crystals.
- Crystals are recognized by their flat faces and sharp angles.
- Euhedral crystals have well-formed flat faces, while anhedral crystals do not.
- Flat faces of a crystal grow larger and smoother over time.
- Crystallographic forms are sets of possible faces related by crystal symmetry.
- A crystal's habit is its visible external shape.
- Crystals have unique physical and chemical properties.
- Some common properties of crystals include transparency, hardness, cleavage, and optical properties.
- Crystals can exhibit various colors due to the presence of impurities or defects in their lattice.
- The arrangement of atoms or molecules in a crystal lattice determines its electrical conductivity.
- Crystals can also exhibit piezoelectric and ferroelectric properties, which make them useful in electronic devices.
- Crystals have a wide range of applications in various industries.
- Gemstones, such as diamonds and rubies, are highly valued for their beauty and rarity.
- Crystals are used in electronics for their electrical and optical properties.
- Some crystals, like quartz, are used in timekeeping devices such as watches and clocks.
- Crystals are also used in scientific research, medicine, and energy storage technologies.
Crystallography and Crystal Systems
- Crystallography is the science of measuring the atomic arrangement of a crystal.
- X-ray diffraction is a widely used crystallography technique.
- Crystallographic databases store large numbers of known crystal structures.
- Crystallography helps understand the properties and behavior of crystals.
- Crystallography has contributed to various fields such as materials science and chemistry.
- Crystals have a repeating pattern of atoms or molecules arranged in a three-dimensional lattice.
- The arrangement of atoms or molecules in a crystal lattice determines its symmetry and crystal system.
- Different crystal systems include cubic, tetragonal, orthorhombic, monoclinic, triclinic, and hexagonal.
- Crystal structures can be described using X-ray crystallography, which reveals the positions of atoms within a crystal lattice.
- Crystallographers use mathematical models and symmetry operations to study and classify crystal structures.
Crystal Formation and Occurrence
- Crystals are formed through a process called nucleation.
- Nucleation occurs when atoms or molecules come together to form a solid structure.
- The arrangement of atoms or molecules in a crystal lattice determines its shape and properties.
- Crystals can form in various environments, including geological, biological, and chemical processes.
- Factors such as temperature, pressure, and chemical composition influence crystal formation.
- Crystals are found in solid bedrock.
- Ice crystals are a natural occurrence.
- Calcite crystals can be found in fossil shells.
- Most inorganic solids are polycrystals.
- Glass is an example of an amorphous solid.
Crystallographic Space Groups and Special Properties
- Crystal structures are characterized by unit cells.
- Unit cells stack to form the crystal.
- There are 219 possible crystal symmetries.
- Crystal symmetries are grouped into 7 crystal systems.
- Each crystal system has specific shapes and arrangements.
- Crystals can have special electrical, optical, and mechanical properties.
- These properties are related to the lack of rotational symmetry in the crystal's atomic arrangement.
- Examples of special properties include the piezoelectric effect and birefringence.
- Electrical conductivity, electrical permittivity, and Young's modulus can vary in different directions in a crystal.
- Glasses or polycrystals can also exhibit these properties if made anisotropic through stress or working.
Crystal Use in Pseudoscientific Practices and Other Concepts
- Crystals are used in crystal therapy.
- They are associated with spellwork in Wiccan beliefs.
- Gemstones are also used in these practices.
- Pseudoscientific beliefs do not have scientific evidence.
- Crystallography is a legitimate scientific study of crystals.
- Crystals range in size from a fraction of a millimeter to several centimeters.
- Exceptionally large crystals can be found, such as the 18m long beryl crystal from Madagascar.
- Crystallization depends on the conditions under which rocks solidify.
- Igneous rocks form from molten magma and can have varying degrees of crystallization.
- Metamorphic rocks like marbles and quartzites undergo recrystallization under high temperature and pressure conditions.
- Water-based ice exists in various forms such as snow, sea ice, and glaciers.
- A snowflake is a single crystal or a collection of crystals.
- Ice crystals can form from cooling liquid water or from supersaturated gaseous solutions.
- Ice expands when it crystallizes, unlike most substances.
- Ice cubes are examples of polycrystals.
- Living organisms can produce crystals like calcite, aragonite, and hydroxylapatite.
- Molluscs produce calcite and aragonite, while bones and teeth contain hydroxylapatite.
- Crystals grown by organisms form from aqueous solutions.
- These crystals play important roles in biological structures and functions.
- Organigenic crystals can have unique properties and structures.
- Polymorphism refers to the ability of a solid to exist in multiple crystal forms.
- Water ice, for example, can exist in hexagonal, cubic, and rhombohedral forms.
- Different polymorphs can have distinct properties and structures.
- Allotropy is the polymorphism observed in pure chemical elements.
- Polymorphism and allotropy contribute to the diverse properties of materials like carbon and steel.
- Crystallization is the formation of a crystalline structure from a fluid or dissolved materials.
- The final form
Crystal Data Sources