- 行业: Mining
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The U.S. Bureau of Mines (USBM) was the primary United States Government agency conducting scientific research and disseminating information on the extraction, processing, use, and conservation of mineral resources.
Founded on May 16, 1910, through the Organic Act (Public Law 179), USBM's missions ...
In crystallography, a form apparently consisting of two sphenoids placed together symmetrically. Compare: disphenoid
Industry:Mining
In crystallography, any element or operation of symmetry involving a mirror or inversion resulting in a change of chirality of an asymmetric unit. Compare: chirality; proper.
Industry:Mining
In crystallography, any one of 230 independent combinations of the 14 essentially different kinds of three-dimensional periodicity (Bravais lattices) with other symmetry operations (point groups, screws, glides). Compare: plane group; Bravais lattice; point group; screw; glide.
Industry:Mining
In crystallography, any symmetry rotation which does not change the chirality (handedness) of an asymmetric unit; e.g., not involving reflection or inversion. Compare: improper
Industry:Mining
In crystallography, having cleavage perpendicular to an axis; said of minerals.
Industry:Mining
In crystallography, having lower symmetry, resulting in forms with half the number of faces as the holohedral point group. Compare: holohedral; merohedral.
Industry:Mining
In crystallography, having no transverse plane of symmetry and no center of symmetry, and composed of forms belonging to only one end of the axis of symmetry.
Industry:Mining
In crystallography, individual crystals of one group united according to different laws.
Industry:Mining
In crystallography, refers to minerals in crystal classes with merohedral symmetry such that crystal forms are different at opposite ends of the crystallographic axes, thus permitting polar crystal properties; e.g., hemimorphite, zincite.
Industry:Mining
