ClipArt ETC
"Orthorhombic. Crystals commonly tabular parallel to basal plane, showing also short prisms and low brachydomes." — Ford, 1912

Marcasite

"Orthorhombic. Crystals commonly tabular parallel to basal plane, showing also short prisms and low…

"Orthorhombic. Crystals commonly tabular parallel to basal plane, showing also short prisms and low brachydomes. The brachydomes usually striated parallel to the brachy-axis. Often twinned, given coxcomb and spear-shaped groups." — Ford, 1912

Marcasite

"Orthorhombic. Crystals commonly tabular parallel to basal plane, showing also short prisms and low…

Orthorhombic Iron Disulphide (Marcasite) sometimes shows cyclic groups of five individuals, bounded by ∞ P, {110} (M); P∞̆, {011} (l); and 0P, {001}, and united into a pentagonal figure by (M) as twinning plane.

Marcasite

Orthorhombic Iron Disulphide (Marcasite) sometimes shows cyclic groups of five individuals, bounded…

This form shows a cube modified by the tetrahedron.

Modified Cube

This form shows a cube modified by the tetrahedron.

"A crystal form does not necessarily make a solid figure. One such an example is this, of the Monoclinic System.

Crystal of the monoclinic system

"A crystal form does not necessarily make a solid figure. One such an example is this, of the Monoclinic…

"The symmetry of the Monoclinic System is as follows: The crystallographic axis b is an axis of binary symmetry and the plane of the a and c axes is a plane of symmetry." — Ford, 1912

Symmetry of monoclinic system

"The symmetry of the Monoclinic System is as follows: The crystallographic axis b is an axis of binary…

An illustration of an octahedral crystal. An octahedron is a polyhedron with eight faces. A regular octahedron is a Platonic solid composed of eight equilateral triangles, four of which meet at each vertex.

Octahedral Crystal

An illustration of an octahedral crystal. An octahedron is a polyhedron with eight faces. A regular…

Represents the combination of an octahedron and a cube, with the octahedron predominate.

Octahedron in Combination with Cube

Represents the combination of an octahedron and a cube, with the octahedron predominate.

Orthoclase

Orthoclase

Orthoclase

Orthoclase.

Orthoclase

Orthoclase.

"Monoclinic. Crystals are usually prismatic in habit and have as prominent forms, clinopinacoid, base, prism, with often smaller orthodomes." — Ford, 1912

Orthoclase

"Monoclinic. Crystals are usually prismatic in habit and have as prominent forms, clinopinacoid, base,…

"Monoclinic. Crystals are usually prismatic in habit and have as prominent forms, clinopinacoid, base, prism, with often smaller orthodomes." — Ford, 1912

Orthoclase

"Monoclinic. Crystals are usually prismatic in habit and have as prominent forms, clinopinacoid, base,…

"Monoclinic. Crystals are usually prismatic in habit and have as prominent forms, clinopinacoid, base, prism, with often smaller orthodomes." — Ford, 1912

Orthoclase

"Monoclinic. Crystals are usually prismatic in habit and have as prominent forms, clinopinacoid, base,…

Natural crystals. 5, orthoclase.

Orthoclase

Natural crystals. 5, orthoclase.

This image represents a twin of the monoclinic mineral Orthoclase. Its twinning plane is the orthopinacoid.

Orthoclase (Twinning)

This image represents a twin of the monoclinic mineral Orthoclase. Its twinning plane is the orthopinacoid.

"This is the general form and is bounded by eight scalene triangles." -The Encyclopedia Britannica 1910

Orthorhombic Bipyramids

"This is the general form and is bounded by eight scalene triangles." -The Encyclopedia Britannica 1910

"This is the general form and is bounded by eight scalene triangles." -The Encyclopedia Britannica 1910

Orthorhombic Bipyramids

"This is the general form and is bounded by eight scalene triangles." -The Encyclopedia Britannica 1910

"general form...bounded by four scalene triangles." -The Encyclopedia Britannica 1910

Orthorhombic Bisphenoid

"general form...bounded by four scalene triangles." -The Encyclopedia Britannica 1910

This is an orthorhombic crystal of olivine. It is formed by the orthorhombic prism in combination with two pinacoids.

Orthorhombic Crystal of Olivine

This is an orthorhombic crystal of olivine. It is formed by the orthorhombic prism in combination with…

This form shows the fundamental prism (p) on a crystal of topaz, in combination with another prism, (p'); the basal pinacoid, (c); the brachydome, (g); and the four pyramids, (o), (o'), (o''), and (x).

Orthorhombic Crystal of Topaz

This form shows the fundamental prism (p) on a crystal of topaz, in combination with another prism,…

A penetration twin of two pentagonal dodecahedrons (known as the iron cross), whose twinning plane is the rhombic dodecahedron, is shown in this figure (Pyrite).

Penetration Twin of Pyrite

A penetration twin of two pentagonal dodecahedrons (known as the iron cross), whose twinning plane is…

"This is bounded by twelve pentagonal faces, but these are not regular pentagons, and the angles over the three sets of different edges are different. The regular dodecahedron of geometry, contained by twelve regular pentagons, is not a possible form in crystals." -The Encyclopedia Britannica 1910

Pentagonal Dodecahedron

"This is bounded by twelve pentagonal faces, but these are not regular pentagons, and the angles over…

"This is the only simple form in this class which differs geometricalled from those of the holosymmetric class...These are each bounded by twenty-four irregular pentagons, and althrough similar to each other they are respectively right- and left-handed..." -The Encyclopedia Britannica 1910

Pentagonal Icositetrahedron

"This is the only simple form in this class which differs geometricalled from those of the holosymmetric…

This crystal is mainly terminated by a rhombohedron of the third order, (x). With this form are associated the prisms of the first and the second order, (m) and (a); another rhombohedron of the third order, (s), and the two rhombohedrons of the first order, (r).

Phenacite

This crystal is mainly terminated by a rhombohedron of the third order, (x). With this form are associated…

"At the freezing point [phosphorus] hardens, becomes brittle, and shows, on being broken, evidences of crystalline structure, the crystals being dodecahedral." —Hallock 1905

Phosphorus

"At the freezing point [phosphorus] hardens, becomes brittle, and shows, on being broken, evidences…

This is a crystal of Polianite, also known as Manganese Dioxide.

Polianite

This is a crystal of Polianite, also known as Manganese Dioxide.

This crystal of Aragonite shows a method of twinning where the twinning plane may remain parallel to itself, so that the alternate individuals are in parallel position. This is called Polysynthetic Twinning.

Polysynthetic Twins

This crystal of Aragonite shows a method of twinning where the twinning plane may remain parallel to…

This form shows a positive and negative tetrahedron in combination.

Positive and Negative Tetrahedron in Combination

This form shows a positive and negative tetrahedron in combination.

The icositetrahedron, 4O4, {411}, on potassium chloride sometimes produces an apparent rhombohedron by the survival of only one fourth of its planes. Two such rhombohedrons, in apparent twinning position, may be derived from the planes of the same icositetrahedron.

Potassium Chloride

The icositetrahedron, 4O4, {411}, on potassium chloride sometimes produces an apparent rhombohedron…

"In this the four lateral planes are rectangular and equal; they may be either oblong or square; in the latter case the form is the cube." —The Encyclopedia Britannica, 1903

Primitive Crystal

"In this the four lateral planes are rectangular and equal; they may be either oblong or square; in…

"If the base is a square and the prism stands erect—that is, if its sides or lateral planes, as they are called, are perpendicular to the base—the form is termed a right square prism." —The Encyclopedia Britannica, 1903

Primitive Crystal

"If the base is a square and the prism stands erect—that is, if its sides or lateral planes, as…

"When the base is a rectangle instead of a square, the form is a right rectangular prism." —The Encyclopedia Britannica, 1903

Primitive Crystal

"When the base is a rectangle instead of a square, the form is a right rectangular prism." —The…

"When the base is a rhombus, and the prism stands erect, the form is a right rhombic prism." —The Encyclopedia Britannica, 1903

Primitive Crystal

"When the base is a rhombus, and the prism stands erect, the form is a right rhombic prism." —The…

"When the base is a rhomboid, and the prism stands erect, it is only the opposite laeral faces that can be equal. The form is called a right rhomboidal prism." —The Encyclopedia Britannica, 1903

Primitive Crystal

"When the base is a rhomboid, and the prism stands erect, it is only the opposite laeral faces that…

"Crystal faces are described according to their relations to the crystallographic axes. A series of numbers which indicate the relative distances by which a face intersects the different axes are called its parameters. " — Ford, 1912

Orthohombie prism

"Crystal faces are described according to their relations to the crystallographic axes. A series of…

A solid having two parallel polygonal bases connected by triangular faces.

Prismatoid

A solid having two parallel polygonal bases connected by triangular faces.

"Crystal faces are described according to their relations to the crystallographic axes. A series of numbers which indicate the relative distances by which a face intersects the different axes are called its parameters. " — Ford, 1912

Orthorhombie pyramid

"Crystal faces are described according to their relations to the crystallographic axes. A series of…

It has been observed that the pentagonal dodecahedron, [∞o2/2], π {201}, on pyrite may have but six of its twelve planes developed in such a manner a to produce an apparent rhombohedron.

Pyrite

It has been observed that the pentagonal dodecahedron, [∞o2/2], π {201}, on pyrite may have but six…

Pyroxene

Pyroxene

Pyroxene

Pyroxene

Pyroxene

Pyroxene

"Terminated usually by a combination of a positive and negative rhombohedron, which often are so equally developed as to give the effect of a hexagonal pyramid." — Ford, 1912

Quartz

"Terminated usually by a combination of a positive and negative rhombohedron, which often are so equally…

"Terminated usually by a combination of a positive and negative rhombohedron, which often are so equally developed as to give the effect of a hexagonal pyramid. Sometimes one rhombohedron predominates or occurs alone. At times the prism faces are wanting, and the combination of the two rhombodendrons gives what appears to be a doubly terminated hexagonal pyramid, known as a quartzoid." — Ford, 1912

Quartz

"Terminated usually by a combination of a positive and negative rhombohedron, which often are so equally…

This illustration shows Quartz or Silica. Quarts is the most abundant mineral in the Earth's continental crust.

Quartz

This illustration shows Quartz or Silica. Quarts is the most abundant mineral in the Earth's continental…

"The quartz crystals are said to be right or left handed, depending upon whether these faces are to be observed trunctuating the edges between prism and rhombohedron." — Ford, 1912

Left-handed quartz

"The quartz crystals are said to be right or left handed, depending upon whether these faces are to…

"The quartz crystals are said to be right or left handed, depending upon whether these faces are to be observed trunctuating the edges between prism and rhombohedron." — Ford, 1912

Right-handed quartz

"The quartz crystals are said to be right or left handed, depending upon whether these faces are to…

"Science has succeeded in classifying the thousands of known crystals in six systems, to each of which belongs a number of forms having some property in common. In order to classify these different crystals, the existence of certain lines within the crystal, called axes, is assumed, around which the form can be symmetrically build up. These axes are assumed to intersect in the center of the crystal, and to pass through from one side to the other." — Hallock, 1905

Regular Octahedron

"Science has succeeded in classifying the thousands of known crystals in six systems, to each of which…

"Science has succeeded in classifying the thousands of known crystals in six systems, to each of which belongs a number of forms having some property in common. In order to classify these different crystals, the existence of certain lines within the crystal, called axes, is assumed, around which the form can be symmetrically build up. These axes are assumed to intersect in the center of the crystal, and to pass through from one side to the other." — Hallock, 1905

Regular Tetrahedron

"Science has succeeded in classifying the thousands of known crystals in six systems, to each of which…

Rhodonite.

Rhodonite

Rhodonite.

"Triclinic. Crystals commonly tabular parallel to base." — Ford, 1912

Rhodonite

"Triclinic. Crystals commonly tabular parallel to base." — Ford, 1912

An alternate combination of manganese meta-silicate (Rhodonite), showing forms: (c), (b), (a), (n), (h), (o), and (s).

Rhodonite

An alternate combination of manganese meta-silicate (Rhodonite), showing forms: (c), (b), (a), (n),…

"Science has succeeded in classifying the thousands of known crystals in six systems, to each of which belongs a number of forms having some property in common. In order to classify these different crystals, the existence of certain lines within the crystal, called axes, is assumed, around which the form can be symmetrically build up. These axes are assumed to intersect in the center of the crystal, and to pass through from one side to the other." — Hallock, 1905

Rhombic Dodecahedron

"Science has succeeded in classifying the thousands of known crystals in six systems, to each of which…

"Bounded by twelve rhomb-shaped faces parallel to the six dodecahedral planes of symetry. the angles between the normals to adjacent faces are 60 degrees...[and] 90 degrees; the indices are {110}" -The Encyclopedia Britannica 1910

Rhombic Dodecahedron

"Bounded by twelve rhomb-shaped faces parallel to the six dodecahedral planes of symetry. the angles…

The rhombic dodecahedron is a convex polyhedron with 12 rhombic faces. It is an Archimedean dual solid, or a Catalan solid. Its dual is the cuboctahedron.

Rhombic Dodecahedron

The rhombic dodecahedron is a convex polyhedron with 12 rhombic faces. It is an Archimedean dual solid,…

This form shows a rhombic dodecahedron (d) combined with the trigonal tristetrahedron (q). It sometimes occurs on Zincblende.

Rhombic Dodecahedron Combined With the Trigonal Tristetrahedron

This form shows a rhombic dodecahedron (d) combined with the trigonal tristetrahedron (q). It sometimes…

"Science has succeeded in classifying the thousands of known crystals in six systems, to each of which belongs a number of forms having some property in common. In order to classify these different crystals, the existence of certain lines within the crystal, called axes, is assumed, around which the form can be symmetrically build up. These axes are assumed to intersect in the center of the crystal, and to pass through from one side to the other." — Hallock, 1905

Rhombohedron

"Science has succeeded in classifying the thousands of known crystals in six systems, to each of which…

Crystal; If the alternate planes of the hexoctahedron extend until the intersect, a new for will result. This form, the Pentagonal Icositetrahedron, is bounded by twenty-four similar but unsymmetrical sides. Naumann's symbol for this form is (m0n/2)r, y{lkh}; Miller's is (m0n/2)l, y{klh}; h>k>l. This form is known as 'right-handed' because it contains the right, top plane of the front, upper octant.

Right-Handed Pentagonal Icositetrahedron

Crystal; If the alternate planes of the hexoctahedron extend until the intersect, a new for will result.…

"Cells of Rumex c, containing raphides r. The cells are called Raphidian. The raphides are acicular or needle-like crystals forming bundles." — Encyclopedia Britanica, 1893

Rumex

"Cells of Rumex c, containing raphides r. The cells are called Raphidian. The raphides are acicular…

Rutile.

Rutile

Rutile.

"Tetragonal. Usually prismatic with pyramid terminations." — Ford, 1912

Rutile

"Tetragonal. Usually prismatic with pyramid terminations." — Ford, 1912

The tetragonal rutile grows upon the rhombohedral titanic iron, so that its prism of the second order, ∞ P ∞ (100), coincides with the basal pinacoid of the latter mineral, while its vertical axis has the direction of one of the intermediate lateral axes of the iron ore.

Rutile Growing Upon Titanic Iron

The tetragonal rutile grows upon the rhombohedral titanic iron, so that its prism of the second order,…