Minerals Vs Crystals: The Differences Between Them
Minerals and crystals are two terms that are often used interchangeably, but they have slightly different meanings. Minerals are naturally occurring, inorganic solids with a definite chemical composition and crystalline structure. Crystals are solids with a regular, repeating arrangement of atoms, molecules, or ions.
All minerals are crystals, but not all crystals are minerals. For example, synthetic crystals such as silicon crystals are not minerals, and organic crystals such as sugar crystals are also not minerals.
Minerals
Minerals are naturally occurring, inorganic substances with a definite chemical composition and a crystalline structure. They are the building blocks of rocks and soil, and they are used in a wide variety of industrial and commercial applications. There are over 4,000 known minerals, and they are the building blocks of rocks.
Minerals Characteristics:
- Chemical Composition: Each type of mineral has a defined chemical composition or a range of compositions due to impurities or substitutions (e.g., olivine can be pure Mg2SiO4 or Fe2SiO4 or a mixture).
- Crystal Structure: At the microscopic level, minerals have an ordered atomic arrangement, but this doesn't necessarily mean they form visible crystals.
- They can appear in a variety of colors, forms, and textures depending on their environment and chemical makeup.
- Minerals have a wide range of physical properties like hardness, color, streak, luster, and cleavage, which help identify them.
Formation: Minerals form through various geological processes, including cooling of magma or lava, precipitation from solutions, metamorphic changes, or through biological processes.
Some examples of minerals include:
- Quartz (SiO₂)
- Mica
- Galena
- Sphalerite
- Gold
- Silver
- Copper
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| The Difference Between Minerals and Crystals. Left: Pair of natural tanzanite crystals! From Arusha Region, Tanzania Credit Left: Anton Watzl Right: Man-made Bismuth crystal |
Crystals
Crystals, on the other hand, are solids with a repeating, three-dimensional arrangement of atoms, molecules, or ions. This arrangement creates a geometric shape, like a cube or pyramid. They can from minerals, but they can also form from other substances, such as organic materials (e.g., sugar crystals) or synthetic materials (e.g., silicon crystals). Crystals have a variety of shapes, including cubes, octahedrons, prisms, and needles.
Crystals Characteristics:
- External Form: Crystals are recognized by their shape, consisting of flat faces with specific, characteristic orientations. However, not all crystals have the opportunity to grow into this ideal form due to space constraints or rapid formation.
- Symmetry: Crystals exhibit symmetry in their structure, which can be seen in the macroscopic form if they are allowed to grow without interference.
- Growth: Crystals grow from a nucleation point in solutions, melts, or gases, where atoms or molecules can attach in an orderly manner, extending the crystal structure
- Can be organic or inorganic.
- Can be formed naturally or artificially.
Formation: Crystals can form from solutions, melts (like magma), or vapors. The formation process requires conditions where atoms or molecules can arrange themselves slowly enough to form a regular structure.
Some examples of crystals include:
- Diamond (crystallized carbon)
- Table Salt (NaCl, halite crystals)
- Snowflakes (ice crystals)
- Amethyst (purple quartz crystal)
- Sugar crystals
- Silicon crystals
Importance
- Crystals have applications in technology and science, including optics (quartz and sapphire), semiconductors (silicon crystals), and crystallography (the study of crystal structures to understand materials).
- Crystals are also important in manufacturing (e.g., synthetic crystals like diamonds or quartz for technological use).
Relationship Between Minerals and Crystals
Crystals and minerals differ, not only through the ways in which they are used but they also differ in terms of structure. To put it simply, a crystal is a structure made up of various natural materials whereas a mineral is a material in itself. Two or more minerals can actually have the same chemical composition and yet completely differ when it comes to crystal structure.
In essence, all minerals are crystals, but not all crystals are minerals. For example, synthetic diamonds (which have a crystalline structure) are not minerals because they are not naturally occurring.
Also, All crystals can be minerals, but not all minerals form visible crystals. Many minerals crystallize under the right conditions, but they may not always exhibit clear external crystalline structures. In contrast, crystals refer strictly to the structure and pattern formed by the atoms within a substance. A substance can be a crystal without being a mineral (e.g., sugar, salt).
Some "minerals" are amorphous (without a definite crystal structure), such as Opal. These are still considered minerals but do not have a long-range atomic order like true crystals.
Common Confusions
Crystal vs. Gem: A gem is a piece of a mineral or crystal that has been cut and polished for use in jewelry. Not all crystals are gems, but many gems are crystals.
Mineraloids: These are substances that resemble minerals but lack a crystalline structure. Examples include Opal and Amber. They are often confused with true minerals.