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Jasper, an aggregate of microgranular quartz and/or cryptocrystalline chalcedony and other mineral phases, [1] [2] is an opaque, [3] impure variety of silica, usually red, yellow, brown or green in color; and rarely blue. The common red color is due to iron(III) inclusions. Jasper breaks with a smooth surface and is used for ornamentation or as ...
Minerals often have a highly distinctive fracture, making it a principal feature used in their identification. Fracture differs from cleavage in that the latter involves clean splitting along the cleavage planes of the mineral's crystal structure, as opposed to more general breakage. All minerals exhibit fracture, but when very strong cleavage ...
This is a list of gemstones, organized by species and types. Minerals There ... Jasper; Petrified wood; Sard; Citrine (var.) Druzy (var.) Flint (var.) Herkimer ...
A conchoidal fracture is a break or fracture of a brittle material that does not follow any natural planes of separation. Mindat.org defines conchoidal fracture as follows: "a fracture with smooth, curved surfaces, typically slightly concave, showing concentric undulations resembling the lines of growth of a shell". [ 1 ]
Orbicular jasper from Madagascar. Orbicular jasper is a variety of jasper which contains variably-colored orbs or spherical inclusions or zones. In highly silicified rhyolite or tuff, quartz and feldspar crystallize in radial aggregates of needle-like crystals which provide the basis or seed for the orbicular structure seen in this kind of jasper. [1]
Some use the term "transform fault" to describe the seismically and tectonically active portion of a fracture zone after John Tuzo Wilson's concepts first developed with respect to the Mid-Atlantic Ridge. [2] The term fracture zone has a distinct geological meaning, but it is also used more loosely in the naming of some oceanic features.
Pages for logged out editors learn more. Contributions; Talk; List of fracture patterns
Such fractures occur in planar parallel sets at an angle of 60 degrees and can be of the same size and scale as joints. As a result, some "conjugate joint sets" might actually be shear fractures. Shear fractures are distinguished from joints by the presence of slickensides, the products of shearing movement parallel to the fracture surface. The ...