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  2. Lineation (geology) - Wikipedia

    en.wikipedia.org/wiki/Lineation_(geology)

    Intersection lineations are measured in relation to the two structures which intersect to form them. For instance, according to the measurement conventions of structural geology , original bedding, S 0 intersected by a fold's axial plane foliation, forms an intersection lineation L 0-1 , with an azimuth and plunge defined by the fold.

  3. Crystal twinning - Wikipedia

    en.wikipedia.org/wiki/Crystal_twinning

    The long horizontal red line is the composition plane where the two crystal segments join. The upper crystal lattice is the reflection of the lower crystal lattice. The red points are the shared crystal lattice points. Twinning, a version of macle, is a form of symmetrical intergrowth between two or more adjacent crystals of the same mineral ...

  4. Line-cylinder intersection - Wikipedia

    en.wikipedia.org/wiki/Line-cylinder_intersection

    Green line has two intersections. Yellow line lies tangent to the cylinder, so has infinitely many points of intersection. Line-cylinder intersection is the calculation of any points of intersection, given an analytic geometry description of a line and a cylinder in 3d space. An arbitrary line and cylinder may have no intersection at all.

  5. Matrix (geology) - Wikipedia

    en.wikipedia.org/wiki/Matrix_(geology)

    Igneous rock, with gray groundmass and white phenocrysts marked. Orthoclase phenocrysts within a finer-grained matrix of a granite porphyry. The matrix or groundmass of a rock is the finer-grained mass of material in which larger grains, crystals, or clasts are embedded.

  6. Rock (geology) - Wikipedia

    en.wikipedia.org/wiki/Rock_(geology)

    Most rocks contain silicate minerals, compounds that include silica tetrahedra in their crystal lattice, and account for about one-third of all known mineral species and about 95% of the earth's crust. [6] The proportion of silica in rocks and minerals is a major factor in determining their names and properties. [7]

  7. Portal:Minerals - Wikipedia

    en.wikipedia.org/wiki/Portal:Minerals

    A rock may consist of one type of mineral or may be an aggregate of two or more different types of minerals, spacially segregated into distinct phases. Some natural solid substances without a definite crystalline structure, such as opal or obsidian, are more properly called mineraloids. If a chemical compound occurs naturally with different ...

  8. Joint (geology) - Wikipedia

    en.wikipedia.org/wiki/Joint_(geology)

    A joint system consists of two or more intersecting joint sets. [1] [2] [3] The distinction between joints and faults hinges on the terms visible or measurable, a difference that depends on the scale of observation. Faults differ from joints in that they exhibit visible or measurable lateral movement between the opposite surfaces of the ...

  9. Pressure-temperature-time path - Wikipedia

    en.wikipedia.org/wiki/Pressure-temperature-time_path

    Metamorphic minerals are unstable upon changing P-T conditions. [1] [3] The original minerals are commonly destroyed during solid state metamorphism and react to grow into new minerals that are relatively stable. [1] [3] Water is generally involved in the reaction, either from the surroundings or generated by the reaction itself. [3]