Properties of crystals
1. Lattice structure: Crystals have a unique and ordered arrangement of atoms or molecules in a repeating pattern called a lattice structure. This lattice structure gives crystals their characteristic geometric shapes.
2. Symmetry: Crystals exhibit various types of symmetry, such as rotational symmetry, reflection symmetry, and translational symmetry. This symmetry is reflected in the external shape of the crystal as well as in the internal arrangement of the atoms or molecules.
3. Cleavage: Crystals have specific planes of weakness along which they can break or cleave when subjected to stress. These cleavage planes are determined by the internal structure of the crystal and can vary depending on the type of crystal.
4. Transparency: Crystals can be transparent, translucent, or opaque depending on their composition and structure. Transparent crystals allow light to pass through them, while opaque crystals block the passage of light. Translucent crystals allow some light to pass through, but they are not completely transparent.
5. Color: The color of a crystal is determined by its composition and the presence of impurities or defects in its structure. Some crystals have a single uniform color, while others exhibit a range of colors due to different impurities present in the crystal lattice.
6. Hardness: Crystals vary in hardness, with some being very hard and resistant to scratching (such as diamond) and others being softer and more easily scratched (such as talc). Hardness is a measure of a crystal's resistance to deformation and is determined by the strength of the bonds between its atoms or molecules.
7. Refraction: Crystals have the ability to refract or bend light as it passes through them due to their ordered internal structure. This property is responsible for the brilliant display of colors seen in some crystals, such as in gemstones.
8. Specific gravity: Crystals have a specific gravity, which is a measure of their density relative to the density of water. This property is determined by the composition and packing arrangement of atoms or molecules in the crystal lattice.
9. Birefringence: Some crystals exhibit birefringence, a property in which light passing through the crystal is split into two rays that travel at different speeds. This property is due to the anisotropic nature of the crystal lattice and is often used in polarized light microscopy to identify and study crystals.