Octahedron and trisoctahedron
"A combination of a trisoctahedron and an octahedron. It will be noted that the faces of the trisoctahedron…
Cube trunctuated by octahedron
"When a corner or an edge of one form is replaced by a face of another form, the first is said to be…
Twinned octahedron
"A contact twin, since the two individuals lie simply in contact with each other upon a certain plane."…
Origin of Springs
A spring is a point where groundwater flows from the ground, and is thus where the aquifer surface meets…
Orographic Blocks
"Unit orographic blocks in granite, near the knife works, Hotchkissville. a Area over downthrown block."…
Orthoclase
"Monoclinic. Crystals are usually prismatic in habit and have as prominent forms, clinopinacoid, base,…
Orthoclase
"Monoclinic. Crystals are usually prismatic in habit and have as prominent forms, clinopinacoid, base,…
Orthoclase
"Monoclinic. Crystals are usually prismatic in habit and have as prominent forms, clinopinacoid, base,…
Outcrop Diagram
"Diagram to illustrate crescentic offsetting of outcrops due to progressively increasing tilting of…
Outcrop Diagram
"Diagram to illustrate crescentic offsetting of outcrops due to progressively increasing throw of orgaraphic…
Outcrop Diagram
"Diagram to illustrate crescentic offsetting of outcrops due to progressive decrease in width of orographic…
Paleozoic Animals
"Fish, trilobites, brachiopods, corals, and graptolites of the Palaeozoic epoch." -Taylor, 1904
Periodical Spring
When the outlet tube of the reservoir is siphon-shaped, the discharge of the spring becomes periodical.…
Plains
The great low plain of North America lies between the Atlantic system on the east and the Pacific system…
Symmetry plane
"A crystal has a center of symmetry if an imaginary line is passed from some point on its surface through…
Platyceras Mollusk
A mollusk radiate from the Paleozoic time, Platyceras angulatum from the Niagara group.
Ditetragonal prism
"The dietetragonal prism is a form consisting of eight rectangular vertical faces, each of which intersects…
Dihexagonal prism
"The dihexagonal prism has twelve rectangular vertical faces, each of which intersects all three of…
First order prism
"The prism of the first order consists of four rectangular vertical faces, each of which intersects…
Orthohombie prism
"Crystal faces are described according to their relations to the crystallographic axes. A series of…
Second order prism
"The prism of the second order consists of four rectangular vertical faces, each of which intersects…
Pterinea Mollusk
A mollusk radiate from the Paleozoic time, Pterinea emacerata from the Niagara group.
Pterygotus anglicus
"Huge fossil Crustacean (Pterygotus Anglicus). Old Red Sandstone, Forfarshire." -Taylor, 1904
Pyramid
"An orthorhombic pyramid has eight triangular faces, each of which intersects all three of the crystallographic…
Dihexagonal pyramid
"The dihexagonal pyramid is a form of twenty-four isoceles triangular faces, each of which intersects…
Ditetragonal pyramid
"The ditetragonal pyramid is a form composed of sixteen isoceles trianglular faces, each of which intersects…
First order pyramid
"The pyramid of the first order is a form consisting of eight isoceles triangular faces, each of which…
Orthorhombie pyramid
"Crystal faces are described according to their relations to the crystallographic axes. A series of…
Second order pyramid
"The pyramid of the second order is a form composed of eight isoceles triangular faces, each of which…
Symmetry of pyritohedral class
"The symmetry of the Pyritohedral class is as follows: The three crystal axes of binary symmetry; the…
Pyritohedron
"This form consists of twelve pentagonal-shaped faces, each of which intersects one crystallographic…
Pyritohedron, cube, and octahedron
"A cube trunctuated with pyritohedron and octahedron." — Ford, 1912
Quartz
"Terminated usually by a combination of a positive and negative rhombohedron, which often are so equally…
Quartz
"Terminated usually by a combination of a positive and negative rhombohedron, which often are so equally…
Quartz
"Terminated usually by a combination of a positive and negative rhombohedron, which often are so equally…
Quartz Sandstone
Thin section of quartz sandstone shown under the microscope. The original rounded quartz grains are…
Left-handed quartz
"The quartz crystals are said to be right or left handed, depending upon whether these faces are to…
Right-handed quartz
"The quartz crystals are said to be right or left handed, depending upon whether these faces are to…