"Resinous luster. Color sulphur-yellow, varying with impurities to yellow shades of green, gray, and red. Transparent to opaque. Imperfect conductor of heat." — Ford, 1912

Sulphur

"Resinous luster. Color sulphur-yellow, varying with impurities to yellow shades of green, gray, and…

"Resinous luster. Color sulphur-yellow, varying with impurities to yellow shades of green, gray, and red. Transparent to opaque. Imperfect conductor of heat." — Ford, 1912

Sulphur

"Resinous luster. Color sulphur-yellow, varying with impurities to yellow shades of green, gray, and…

This table-top is made from the marble of Derbyshire, England. It also is made out of lapis lazuli a semi-precious stone and malachite a mineral. The center of the table has a design of birds and flowers.

Table-Top

This table-top is made from the marble of Derbyshire, England. It also is made out of lapis lazuli a…

"Monoclinic. Crystals varied in habit. Often with prominent basal plane which is steeply inclined and which in combination with short prism and pyramid faces gives a thin wedge-shaped crystal." — Ford, 1912

Titanite

"Monoclinic. Crystals varied in habit. Often with prominent basal plane which is steeply inclined and…

"Monoclinic. Crystals varied in habit. Often with prominent basal plane which is steeply inclined and which in combination with short prism and pyramid faces gives a thin wedge-shaped crystal." — Ford, 1912

Titanite

"Monoclinic. Crystals varied in habit. Often with prominent basal plane which is steeply inclined and…

Topaz.

Topaz

Topaz.

Topaz.

Topaz

Topaz.

Topaz

Topaz

Topaz

"Orthohombic. In prismatic crystals terminated by pyramids, domes, and basal plane." — Ford, 1912

Topaz

"Orthohombic. In prismatic crystals terminated by pyramids, domes, and basal plane." — Ford, 1912

"Tourmaline crystals show the forms of the Rhombohedral Class but with hemispherical development. They are also commonly characterized by the presence of three faces of a triangular prism." — Ford, 1912

Tourmaline

"Tourmaline crystals show the forms of the Rhombohedral Class but with hemispherical development. They…

"Tourmaline crystals show the forms of the Rhombohedral Class but with hemispherical development. They are also commonly characterized by the presence of three faces of a triangular prism." — Ford, 1912

Tourmaline

"Tourmaline crystals show the forms of the Rhombohedral Class but with hemispherical development. They…

"Tourmaline crystals show the forms of the Rhombohedral Class but with hemispherical development. They are also commonly characterized by the presence of three faces of a triangular prism." — Ford, 1912

Tourmaline

"Tourmaline crystals show the forms of the Rhombohedral Class but with hemispherical development. They…

"Hexagonal-rhombohedral; hemimorphic. Crystals usually prismatic, vertically striated. A triangular prism, with three faces, prominent, which with the tendency of the prism faces to be vertically striated and to round into each other gives the crystals usually a cross section like a spherical triangle." — Ford, 1912

Tourmaline

"Hexagonal-rhombohedral; hemimorphic. Crystals usually prismatic, vertically striated. A triangular…

"Hexagonal-rhombohedral; hemimorphic. Crystals usually prismatic, vertically striated. A triangular prism, with three faces, prominent, which with the tendency of the prism faces to be vertically striated and to round into each other gives the crystals usually a cross section like a spherical triangle. Crystals are commonly terminated by base and low positive and negative rhombohedrons; sometimes scalenohedrons are present. When the crystals are doubly terminated they usually show different forms at the opposite ends of the vertical axis." — Ford, 1912

Tourmaline

"Hexagonal-rhombohedral; hemimorphic. Crystals usually prismatic, vertically striated. A triangular…

Vesuvianite.

Vesuvianite

Vesuvianite.

Vesuvianite

Vesuvianite

Vesuvianite

"Tetragonal. Prismatic in habit. Often vertically striated. Common forms are prisms of first and second orders, pyramid of first order and base." — Ford, 1912

Vesuvianite

"Tetragonal. Prismatic in habit. Often vertically striated. Common forms are prisms of first and second…

"Tetragonal. Prismatic in habit. Often vertically striated. Common forms are prisms of first and second orders, pyramid of first order and base." — Ford, 1912

Vesuvianite

"Tetragonal. Prismatic in habit. Often vertically striated. Common forms are prisms of first and second…

This form shows a very complex combination of thirteen tetragonal forms occuring on the mineral Vesuvianite: the prism of the first order, (d); prism of the second order, (M); basal pinacoid, (s); three pyramids of the first order, (c), (b), and (u); the ditetragonal prism (f); and the four ditetragonal pyramids (z), (x), (e), and (a).

Vesuvianite

This form shows a very complex combination of thirteen tetragonal forms occuring on the mineral Vesuvianite:…

"Tetragonal; tripyramidal. Crystals usually prismatic. Prominent forms are prisms of the first and second order, pyramid of first." — Ford, 1912

Wernerite

"Tetragonal; tripyramidal. Crystals usually prismatic. Prominent forms are prisms of the first and second…

"Tetragonal; tripyramidal. Crystals usually prismatic. Prominent forms are prisms of the first and second order, pyramid of first. Rarely shows the faces of the pyramid of the third order." — Ford, 1912

Wernerite

"Tetragonal; tripyramidal. Crystals usually prismatic. Prominent forms are prisms of the first and second…

Zircon.

Zircon

Zircon.

Zircon.

Zircon

Zircon.

Zircon.

Zircon

Zircon.

Zircon.

Zircon

Zircon.

"Tetragonal. Crystals usually show a simple combination of prism and pyramid of the first order. The prism of the second order and a ditetragonal pyramid also at times observed." — Ford, 1912

Zircon

"Tetragonal. Crystals usually show a simple combination of prism and pyramid of the first order. The…

In the tetragonal system, the unit pyramid of the second order is the most common twinning plane. This is represented here as it occurs on crystals of Zircon, bounded by the forms (m), (u), (p), and (o).

Zircon (Twinning)

In the tetragonal system, the unit pyramid of the second order is the most common twinning plane. This…