Some Basic Mineralogy:

     Mineral: A mineral is a naturally occurring inorganic solid with a definite chemical composition and an ordered internal atomic arrangement.

     Rock: A rock is a naturally formed combination of two or more minerals, either consolidated or not(except soil), with some degree of mineralogical consistency.

Chemical Bonding

     Ionic bonds- one ion gives up an electron to another ion when two bond to fulfill the 'octet rule'
     Covalent bonds- two ions share an electron so that both fulfill the 'octet rule'
     Metallic bonds- a free electron floats around in space creating an electrical charge
     Van der Waal bonds- ions are electrically attracted to one another but no electrons are shared

Crystal Systems:

     Isometric- The three crystallographic axes are all in equal length and intersect at right angles(90 degrees) to one another
     
     Tetragonal- Three axes, all at right angles, two of which are equal in length (A and B) and one (C) which is different in length (shorter or longer). Note: If C was equal in length to A then this would be the isometric system.

     Orthorhombic- Three axes, all at right angles, and all three of different lengths. Note: If any axis was of equal length to any other, then this would be the tetragonal system.
     Monoclinic- Three axes, all unequal in length, two of which (A and C) intersect at an oblique angle (not 90 degrees), the third axis (B) is perpendicular to the other two axes. Note: If A and C crossed at 90 degrees, then this would be the orthorhombic system.      Triclinic- The three axes are all unequal in length and intersect at three different angles (any angle but 90 degrees). Note: If any two axes crossed at 90 degrees, then this would be the monoclinic system.

     Hexagonal- This system has four axes. Three of the axes at 120 degrees between the positive ends. These 3 axes, labeled a1, a2, and a3, are the same length. The fourth axis, termed c, may be longer or shorter than the a set. The c axis also passes through the intersection of the a axes set at a right angle to the plane formed by the set.