Silicates Definition In the fields of geology and mineralogy, the term “silicates” refers to compounds whose crystal structure contains SiO4 tetrahedra. Silicates are either isolated or joined to form groups, rings, single or double chains, sheets, or three-dimensional frameworks.

Surface-Wave Magnitude “Surface-Wave Magnitude” is the magnitude of an earthquake that scientists estimate using measurements of the amplitude of surface waves.

Contact Metamorphism Contact Metamorphism – Metamorphism is associated with the intrusion of an igneous mass. Metamorphic changes are caused principally by heat, but also by magma composition and deformation related to the intrusion. Pressures are relatively low (<3000 bars) while temperatures range from 200°C to 1000°C.

Rigidity Definition Rigidity – In geotechnical engineering and engineering geology, rigidity represents the ratio of the shear stress and the amount of angular rotation that it produces, within a rock sample.