4.4 - Halite Packing- Arrangement of Atoms in a Halite Crystal -- the green are chlorine atoms and the yellow are smaller sodium atoms.
4.4 - Cube- Atoms fit together in a limited number of ways. How closely atoms can be packed together depends on their electrical charge and the relative size of different kinds of atoms. Atoms can be arranged in the shape of a cube. This type of structure is referred to as cubic.
4.4 - Tetrahedron- Atoms fit together in a limited number of ways. How closely atoms can be packed together depends on their electrical charge and the relative size of different kinds of atoms. Atoms can also be arranged as a pyramid with three sides and a base. This arrangement and four-sided shape is called a tetrahedron (tetra=four).
4.4 - Octahedron- Atoms fit together in a limited number of ways. How closely atoms can be packed together depends on their electrical charge and the relative size of different kinds of atoms. Atoms can also be arranged in a shape that is like two oppositely pointing, four-sided pyramids joined at their bases. This shape is an octahedron (octa=eight).
4.5 - Cleavage- The crystal lattice of this mineral consists of three kinds of atoms shown in brown, blue, and gray. The brown atoms are linked or bonded with the blue atoms in flat sheets. Adjacent sheets are joined together by bonds between the gray atoms and the brown atoms in the sheets. Bonds between the brown and blue atoms are stronger than bonds between the brown and gray atoms. If the mineral is subjected to sufficient forces, it will break along the easiest direction, through the weakest bonds (those between the brown and gray atoms). The break will occur along the cleavage planes shown in yellow.
4.5 - Halite Cleavage- The bonds in this mineral all have the same strength but are arranged in such a way that the mineral can break along three sets of planes without passing through an atom. In this example, the three planes are mutually perpendicular (at 90 degrees to each other).
4.5 - Irregular Fracture- The atoms in this mineral are arranged so that a break can cut through the lattice in nearly any direction. This mineral will break along an irregular fracture instead of cleavage planes.
4.5 - Biotite- One direction of cleavage - If a mineral has a single direction of cleavage, it cleaves along one set of parallel planes forming thin sheets.
4.5 - Pyroxene- Two Perpendicular Directions of Cleavage - Many minerals cleave along two sets of planes that are perpendicular to one another. This type of cleavage results in right-angle (90 degree) steps along broken crystal faces.
4.5 - Amphibole- Two Non-Perpendicular Directions of Cleavage - Two planes of cleavage can intersect at angles other than 90 degrees. Minerals with this type of cleavage can break into pieces having corners that do not form right angles.
4.5 - Halite Solid- Three Perpendicular Directions of Cleavage - If a mineral cleaves along three perpendicular sets of planes, broken faces have a stair-step geometry and the mineral commonly breaks into cubes.
4.5 - Calcite- Three Non-Perpendicular Directions of Cleavage - Minerals that cleave along three directions of planes that are not mutually perpendicular break into pieces that are shaped like a rhomb, or a sheared box.
4.10 - Periodic Table Abundances- What elements are common in the crust, whole earth, and solar system? Click and drag upward to scroll between the different abundances.
Additional Resource: Common Minerals and Their Uses
Additional Resource: Mineral Resources Program
Additional Resource: Index of minerals in thin section