A crystal or crystalline solid is a solid material
whose constituents (such as atoms, molecules, or ions) are arranged how?
A: In a highly ordered microscopic structure, forming a crystal lattice that
extends in all directions.
In addition, macroscopic single crystals are usually
identifiable by what?
A: Their geometrical shape, consisting of flat faces with specific,
characteristic orientations.
The scientific study of crystals and crystal formation
is known as what?
A: Crystallography.
What is the process of crystal formation via mechanisms
of crystal growth called?
A: Crystallization or solidification.
Examples of large crystals include what?
A: Snowflakes, diamonds, and table salt.
Most inorganic solids are not crystals but what?
A: Polycrystals, i.e. many microscopic crystals fused together into a single
solid.
Examples of polycrystals include what?
A: Most metals, rocks, ceramics, and ice.
A third category of solids is amorphous solids, where
the atoms have what?
A: No periodic structure whatsoever.
Examples of amorphous solids include what?
A: Glass, wax, and many plastics.
By volume and weight, the largest concentrations of
crystals in the Earth are part of its what?
A: Solid bedrock.
As of 1999, the world's largest known naturally
occurring crystal is what?
A: A crystal of beryl from Malakialina, Madagascar, 18 m (59 ft) long and
3.5 m (11 ft) in diameter and weighing 380,000 kg (840,000 lb).
Some crystals have formed by magmatic and metamorphic
processes, giving origin to what?
A: Large masses of crystalline rock.
Most igneous rocks are formed from molten magma and the
degree of crystallization depends on what?
A: Primarily on the conditions under which they solidified.
What is polymorphism?
A: The ability of a solid to exist in more than one crystal form.
For pure chemical elements, polymorphism is known as
what?
A: Allotropy.
For example, diamond and graphite are two crystalline
forms of what?
A: Carbon.
Polymorphs may have wildly different what?
A: Properties.
For example, diamond is among the hardest substances
known, while graphite is what?
A: So soft that it is used as a lubricant.
An ideal crystal has every atom in a what?
A: A perfect, exactly repeating pattern.
However most crystalline materials have a variety of
crystallographic defects, places where the crystal's pattern is what?
A: Interrupted.
In semiconductors, a special type of impurity, called a
dopant, drastically changes the crystal's what?
A: Electrical properties.
