Fundamental Minerals

Sialic Minerals

Feldspar

Feldspathoid

Quartz

Femic Minerals

Accessory Minerals

Very Rare Minerals

Secondary Minerals

Texture

Alteration Products

Glass and related Texture

Volcanic Rocks

Komatiites

Lamprophyres

Pseudomorph

Pseudomorph ("false form"), is a mineral formed by chemical or structural change of another substance, though retaining its original external shape. Although pseudomorphs give the appearance of being crystalline, they are commonly granular and waxy internally and have no regular cleavage; those that are crystalline have optical properties different from those required by their outward form.

Pseudomorphs are formed by substitution, deposition, or alteration:

• In the formation of a pseudomorph by substitution, the original substance has been gradually removed and simultaneously replaced by another. A common example of this is petrified wood, in which all the cellulose fibres have been replaced by silica, even those in the bark.

• Pseudomorphs can be formed by deposition of one mineral on the surface of crystals of another.

• Alteration pseudomorphs may be formed in several ways: from a change in internal crystal structure without a change in chemical composition (these pseudomorphs are called paramorphs; e.g., aragonite becomes calcite, and brookite becomes rutile); by the loss of an ingredient from the original compound (e.g., cuprite loses oxygen to form copper); by the addition of an ingredient to the original compound (e.g., anhydrite adds water to form gypsum, and cuprite adds carbon dioxide and water to form malachite); and by an exchange of constituents (e.g., feldspar loses potassium silicate and gains water to become kaolinite).

Bibliography

• Cox et al. (1979): The Interpretation of Igneous Rocks, George Allen and Unwin, London.
• Howie, R. A., Zussman, J., & Deer, W. (1992). An introduction to the rock-forming minerals (p. 696). Longman.
• Le Maitre, R. W., Streckeisen, A., Zanettin, B., Le Bas, M. J., Bonin, B., Bateman, P., & Lameyre, J. (2002). Igneous rocks. A classification and glossary of terms, 2. Cambridge University Press.
• Middlemost, E. A. (1986). Magmas and magmatic rocks: an introduction to igneous petrology.
• Shelley, D. (1993). Igneous and metamorphic rocks under the microscope: classification, textures, microstructures and mineral preferred-orientations.
• Vernon, R. H. & Clarke, G. L. (2008): Principles of Metamorphic Petrology. Cambridge University Press.

Olivine pseudomorphed by talc. XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by talc. XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by talc. XPL image, 10x (Field of view = 2mm)
Olivine pseudomorphed by talc. XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by talc. XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by talc. XPL image, 10x (Field of view = 2mm)
Olivine pseudomorphed by talc. XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by talc. XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by talc and Calcite (high relief). PPL image, 10x (Field of view = 2mm)
Pyroxene pseudomorphed by Calcite (at the core). Milos (Greece). XPL image, 10x (Field of view = 2mm)	Pyroxene pseudomorphed by Calcite (at the core). Milos (Greece). XPL image, 10x (Field of view = 2mm)	Pyroxene pseudomorphed by Calcite (at the core). Milos (Greece). XPL image, 10x (Field of view = 2mm)
Pyroxene and Olivine (right) pseudomorphed by Calcite (at the core). Milos (Greece). XPL image, 10x (Field of view = 2mm)	Pyroxene pseudomorphed by Calcite (at the core). Milos (Greece). XPL image, 10x (Field of view = 2mm)	Pyroxene pseudomorphed by Calcite (at the core). Milos (Greece). XPL image, 10x (Field of view = 2mm)
Pyroxene pseudomorphed by Calcite (at the core). Milos (Greece). XPL image, 10x (Field of view = 2mm)	Pyroxene pseudomorphed by Calcite (at the core). Milos (Greece). PPL image, 10x (Field of view = 2mm)	Pyroxene pseudomorphed by Calcite (at the core). Milos (Greece). XPL image, 10x (Field of view = 2mm)
Olivine pseudomorphed by Calcite. XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by Calcite. PPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by Calcite. XPL image, 10x (Field of view = 2mm)
Olivine pseudomorphed by Calcite. XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by Calcite. XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by Calcite. PPL image, 10x (Field of view = 2mm)
Olivine pseudomorphed by Calcite. XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by Calcite. PPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by Calcite. PPL image, 10x (Field of view = 2mm)
Olivine pseudomorphed by Calcite. XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by talc. PPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by talc. XPL image, 10x (Field of view = 2mm)
Olivine pseudomorphed by talc. XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by talc. XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by talc. XPL image, 10x (Field of view = 2mm)
Olivine pseudomorphed by talc. PPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by talc. XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by talc. XPL image, 10x (Field of view = 2mm)
Olivine pseudomorphed by talc. XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by talc. XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by talc. XPL image, 10x (Field of view = 2mm)
Pyroxene pseudomorphed by Chlorite. XPL image, 10x (Field of view = 2mm)	Pyroxene pseudomorphed by Chlorite. XPL image, 10x (Field of view = 2mm)	Pyroxene pseudomorphed by Chlorite. XPL image, 10x (Field of view = 2mm)
Pyroxene pseudomorphed by Chlorite. XPL image, 10x (Field of view = 2mm)	Pyroxene pseudomorphed by Chlorite. XPL image, 10x (Field of view = 2mm)	Feldspar pseudomorphed by Sericite. XPL image, 10x (Field of view = 2mm)
Feldspar pseudomorphed by Sericite. XPL image, 2x (Field of view = 7mm)	Feldspar pseudomorphed by Sericite. XPL image, 10x (Field of view = 2mm)	Feldspar pseudomorphed by Sericite. XPL image, 10x (Field of view = 2mm)
Feldspar pseudomorphed by Sericite. XPL image, 2x (Field of view = 7mm)	Olivine pseudomorphed by talc. XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by talc. XPL image, 10x (Field of view = 2mm)
Olivine pseudomorphed by Calcite. Pergamon (Turkey). XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by Calcite. Pergamon (Turkey). XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by Calcite. Pergamon (Turkey). XPL image, 10x (Field of view = 2mm)
Olivine pseudomorphed by Calcite. Pergamon (Turkey). XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by Calcite. Pergamon (Turkey). XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by Calcite. Pergamon (Turkey). XPL image, 10x (Field of view = 2mm)
< Olivine pseudomorphed by Calcite. Pergamon (Turkey). XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by Calcite. Pergamon (Turkey). XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by Calcite. Pergamon (Turkey). XPL image, 10x (Field of view = 2mm)
Olivine pseudomorphed by Calcite. Pergamon (Turkey). XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by Calcite. Pergamon (Turkey). XPL image, 10x (Field of view = 2mm)	Olivine pseudomorphed by Calcite. Pergamon (Turkey). XPL image, 10x (Field of view = 2mm)
Pyroxene pseudomorphed by Chlorite. Pergamon (Turkey). XPL image, 10x (Field of view = 2mm)	Pyroxene pseudomorphed by Chlorite. Pergamon (Turkey). XPL image, 10x (Field of view = 2mm)	Pyroxene pseudomorphed by Chlorite. Pergamon (Turkey). XPL image, 10x (Field of view = 2mm)
Pyroxene pseudomorphed by Chlorite. Pergamon (Turkey). PPL image, 10x (Field of view = 2mm)	Pyroxene pseudomorphed by Chlorite. Pergamon (Turkey). XPL image, 10x (Field of view = 2mm)	Pyroxene pseudomorphed by Chlorite. Pergamon (Turkey). XPL image, 10x (Field of view = 2mm)
Pyroxene pseudomorphed by Chlorite. Pergamon (Turkey). PPL image, 10x (Field of view = 2mm)	Pyroxene pseudomorphed by Chlorite. Pergamon (Turkey). XPL image, 10x (Field of view = 2mm)