Properties of Minerals

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Mineral Noun

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[min-er-uhl]

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Mineral

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A naturally occurring, inorganic, crystalline solid that possesses a definite chemical composition and a unique set of physical properties.

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Example: This image shows a quartz crystal, a common mineral. Its sharp edges and flat, geometric faces demonstrate a mineral's key property: a definite crystalline structure.

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Naturally Occurring Adjective

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[nach-er-uh-lee uh-kur-ing]

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Naturally Occurring

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A characteristic of a substance that is formed by natural processes and is not created or manufactured by people.

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Example: This image compares examples of minerals and rocks. It does not illustrate what 'naturally occurring' means and incorrectly classifies several items, such as listing a rock (Scoria) under minerals.

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Inorganic Adjective

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[in-or-gan-ik]

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Inorganic

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A substance that does not originate from living organisms and typically lacks the carbon-hydrogen bonds characteristic of organic matter.

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Example: This image shows examples of inorganic compounds, like salt (NaCl) and rust (an oxide), which are substances not typically made by living organisms.

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Crystal Noun

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[kris-tl]

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Crystal

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A solid material whose constituent atoms, molecules, or ions are arranged in a highly ordered, repeating microscopic structure.

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Example: A crystal is a solid where atoms are arranged in an ordered, repeating pattern, called a crystal lattice, which is shown for quartz, salt, and ice.

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Crystal Structure Noun

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[kris-tl struhk-cher]

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Crystal Structure

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The specific, repeating, three-dimensional arrangement of atoms or particles within a crystalline solid, which determines its shape.

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Example: A crystal structure is the orderly, repeating arrangement of atoms in a solid, like the organized honeycomb pattern on the left, not the random one.

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Definite Chemical Composition Noun

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[def-uh-nit kem-i-kuhl kom-puh-zish-uhn]

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Definite Chemical Composition

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The principle that a mineral always contains specific elements combined in fixed, definite proportions by mass.

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Example: This diagram shows the mineral halite (salt) is always made of sodium and chlorine atoms in a fixed, repeating 1-to-1 pattern.

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Element Noun

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[el-uh-muhnt]

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Element

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A pure substance consisting of only one type of atom that cannot be broken down into simpler substances by chemical means.

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Example: This diagram shows an atom of the element Oxygen, which is defined by its specific number of protons (8) in the nucleus.

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Compound Noun

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[kom-pound]

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Compound

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A substance formed when two or more different chemical elements are chemically bonded together in a fixed, definite ratio.

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Example: This diagram shows a carbon dioxide (CO₂) molecule, where one carbon atom is chemically bonded to two oxygen atoms, forming a compound.

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Streak Noun

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[streek]

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Streak

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The color of a mineral's powder, which is observed by rubbing the mineral across an unglazed porcelain plate.

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Example: This image shows different minerals being scraped on white tiles, leaving behind colored powders, which demonstrates the concept of a mineral's streak.

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Luster Noun

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[luhs-ter]

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Luster

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The way light interacts with and reflects from the surface of a mineral, described as metallic or non-metallic.

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Example: This image shows two minerals, pyrite and galena, that reflect light like polished metal, which is the definition of metallic luster.