Fundamental Minerals

Sialic Minerals

• Feldspars
Feldspars minerals
Alkali Feldspars
Plagioclase

• Feldspathoids
Feldspathoids
Cancrinite
Haüyne
Leucite
Nepheline
Sodalite

• Quartz

Femic Minerals

• Amphiboles
• Biotite
• Sagenitic biotite
• Kaersutite
• Olivine
• Pyroxenes
Structure/classification
Clinopyroxene

• Spodumene

Accessory Minerals

• Apatite
• Chromite
• Ilmenite
• Magnetite
• Zircon

Rare Accessory

• Allanite
• Andalusite
• Astrophyllite
• Beryl
• Calcite
• Cancrinite
• Catapleiite
• Cordierite
• Diaspore
• Eudialyte
• Fluorite
• Garnets
• Lazulite
• Lamprophyllite
• Lorenzenite
• Monticellite
• Muscovite
• Natrolite
• Naujakasite
• Niocalite
• Perovskite
• Polylithionite
• Rosenbuschite
• Rutile
• Scapolite
• Sørensenite
• Titanite
• Topaz
• Tourmaline
• Tugtupite
• Ussingite
• Wollastonite
• Xenotime
• Zinnwaldite

Alteration Products

• Chlorite
• Saussurite
• Sericite
• Uralite
• Wairakite

Microstructures

• Antiperthite
• Exsolution lamellae
• Graphic texture
• Granophyric texture
• Magmatic flow
• Myrmekite
• Pleochroic halo
• Poikilitic texture
• Perthite
• Pseudoleucite
• Zoning

Rocks

• Alkali feldspar granite
• Alkali feldspar syenite
• Alnö complex
Alnö complex
Alnöite
Sövite

• Anorthosite
• Brandberg granites
• Borolanite
• Carbonatites
Carbonatites
Alnö (Sweden)
Fogo (C. Verde)
Sao Vicente (C. Verde)
Oka (Canada)
Sokli (Finland)
Valentine (Canada)

• Cumberlandite
• Cumulate rocks
Cumulate
Adcumulate
Orthocumulate

• Diorite
• Dunite (Dun)
• Ekerite
• Eurite
• Finero harzburgite
• Foidolite (leucite)
• Foidolite (nepheline)
• Foidolite (haüyne)
• Foyaite
• Gabbro
• Gabbro "eufodite"
• Gabbro with augite
• Gabbronorite
• Granite
• Granophyre
• Greisen
• Hornblendite
• Hornblendite (cpx-hbl)
• Hornblende gabbro
• Hornblende gabbro (Adamello)
• Ijolite
• Ijolite (Magnet Cove)
• Ilimaussaq magmatic complex
Ilimaussaq
Black kakortokite
Red kakortokite
White kakortokite
Lujavrite
Naujakasite lujavrite
Naujaite
Tugtupite syenite

• Jacupiranga complex
Jacupiranga
Sövite

• Jacupirangite (Alnö)
• Jotunite
• Italite
• Kakortokite
• Kaxtorpite
• Kentallenite
• Lakarpite
• Larvik
Larvik complex
Ekerite
Larvikite

• Lherzolite (TL)
• Leucogranite
• Lujavrite
• Lugarite
• Luxullianite
• Melilitolite
• Melilitolite (wollastonite)
• Melteigite
• Monzonite
• Monzodiorite
• Naujaite
• Nepheline syenite
• Norra Kärr complex
Norra Kärr
Kaxtorpite
Lakarpite
Pulaskite

• Norite
• Olivine hornblendite
• Oka complex
Oka complex
Niocalite carbonatite
Monticellite carbonatite

• Olivine gabbro
• Orthopyroxenite
• Pegmatite
• Pegmatite (cancrinite)
• Pegmatite (nepheline)
• Peralkaline granite
• Peridotites
Peridotites
Dunite
Wherlite
Harzburgite
Garnet lherzolite
Spinel lherzolite

• Pyroxenite
• Pulaskite
• Quartz-gabbro
• Rhum layerded complex
• Serpentinized lherzolite
• Syenite
• Synnyrite
• Syenogranite
• Sodalite syenite
• Tonalite
• Troctolite
• Urtite

Peralkaline granite

Granite is a medium-tocoarse-grained acid igneous rock with essential quartz (>20%) and feldspar, where alkali feldspar constitutes between 100 and 35% of the feldspars, and minor mafic minerals. Hornblende and biotite are the commonest mafic minerals, however, muscovite is also frequently encountered. Pyroxene, andalusite, corundum, tourmaline, garnet and topaz are also relatively common mafic minerals. Rhyolite is the fine-grained equivalent of granite.

Granites are subdivided on the basis of the relative proportion of alkali feldspar to plagioclase feldspar into monzogranites (65-35% alkali feldspar), syenogranites (90-65% alkali feldspar), and alkali granites (>90% alkali feldspar). Around 70% of granites are monzogranites. Aplites are equigranular granitic rocks with little mafic component occurring in veins or dykes. Granophyres are granitic rocks in which quartz and feldspar has a granophyric intergrowth.

Granites can be subdivided on the basis of their chemistry into peralkaline, metaluminous, and peraluminous on the basis of the ratio Al₂O₃/(Na₂O + K₂O + CaO). The related terminology is:

• peraluminous: Al₂O₃ > (Na₂O + K₂O + CaO) or Al₂O₃/(Na₂O + K₂O + CaO) > 1.1; Rock will probably have muscovite and may have garnet; will be corundum-normative.
• metaluminous: Al₂O₃ < (Na₂O + K₂O + CaO) but Al₂O₃ > (Na₂O + K₂O) or Al₂O₃/(Na₂O + K₂O + CaO) > 1.0; rock may have hornblende
• subaluminous: Al₂O₃ < (Na₂O + K₂O + CaO) but Al₂O₃ = (Na₂O + K₂O); Al₂O₃/(Na₂O + K₂O + CaO) < 1.0; rock will probably have hornblende; will have Di in the norm.
• peralkaline: Al₂O₃ < (Na₂O + K₂O) or Al₂O₃/(Na₂O + K₂O + CaO) << 1.0; rock will probably have lot of K-feldspar in the norm, probably a feldspathoid or very little, if any quartz.

But Granites can be subdivided also on the basis of the infered genesis into I-type, S-type, M-type and A-type. Chappell & White classification system was proposed initially to divide granites into I-type granite (or igneous protolith) granite and S-type or sedimentary protolith granite. Both of these types of granite are formed by melting of high grade metamorphic rocks, either other granite or intrusive mafic rocks, or buried sediment, respectively.
M-type or mantle derived granite was proposed later, to cover those granites which were clearly sourced from crystallized mafic magmas, generally sourced from the mantle. These are rare, because it is difficult to turn basalt into granite via fractional crystallisation.
A-type or anorogenic granites are formed above volcanic "hot spot" activity and have peculiar mineralogy and geochemistry. These granites are formed by melting of the lower crust under conditions that are usually extremely dry. The rhyolites of the Yellowstone caldera are examples of volcanic equivalents of A-type granite. H-type or hybrid granites are formed following a mixing of two granitic magmas from different sources, e.g. M-type and S-type.

Peralkaline granite with fayalite (iron-rich end-member of olivine group). From (Sandatlas). Norway.

Peralkaline granite with riebeckite (blue-balck). From (Virtual microscope). Isle of Ailsa Craig lies in the Firth of Clyde, Scotland.

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.

Photo

Aegirine (grass-green) and orthose crystals (colorless). Gariboldi (or Kone) Caldera, Ethiopia. PPL image, 2x (Field of view = 7mm)	Aegirine crystals (high interference colors), orthose crystals (I order gray, with perthite unmixing) and quartz (I order gray). Gariboldi (or Kone) Caldera, Ethiopia. XPL image, 2x (Field of view = 7mm)	Aegirine crystals (high interference colors), orthose crystals (I order gray, with perthite unmixing) and quartz (I order gray). Gariboldi (or Kone) Caldera, Ethiopia. XPL image, 2x (Field of view = 7mm)
Aegirine (grass-green) and orthose crystals (colorless). Gariboldi (or Kone) Caldera, Ethiopia. PPL image, 2x (Field of view = 7mm)	Aegirine crystals (high interference colors), orthose crystals (I order gray, with perthite unmixing) and quartz (I order gray). Gariboldi (or Kone) Caldera, Ethiopia. XPL image, 2x (Field of view = 7mm)	Aegirine (grass-green) and orthose crystals (colorless). Gariboldi (or Kone) Caldera, Ethiopia. PPL image, 2x (Field of view = 7mm)
Aegirine crystals (high interference colors), orthose crystals (I order gray, with perthite unmixing) and quartz (I order gray). Gariboldi (or Kone) Caldera, Ethiopia. XPL image, 2x (Field of view = 7mm)	Aegirine (grass-green) and orthose crystals (colorless). Gariboldi (or Kone) Caldera, Ethiopia. PPL image, 10x (Field of view = 2mm)	Aegirine (grass-green) and orthose crystals (colorless). Gariboldi (or Kone) Caldera, Ethiopia. PPL image, 10x (Field of view = 2mm)
Aegirine (grass-green) and orthose crystals (colorless). Gariboldi (or Kone) Caldera, Ethiopia. PPL image, 10x (Field of view = 2mm)	Aegirine crystals (high interference colors), orthose crystals (I order gray, with perthite unmixing) and quartz (I order gray). Gariboldi (or Kone) Caldera, Ethiopia. XPL image, 10x (Field of view = 2mm)	Aegirine (grass-green) and orthose crystals (colorless). Gariboldi (or Kone) Caldera, Ethiopia. PPL image, 2x (Field of view = 7mm)
Aegirine crystals (high interference colors), orthose crystals (I order gray, with perthite unmixing) and quartz (I order gray). Gariboldi (or Kone) Caldera, Ethiopia. XPL image, 2x (Field of view = 7mm)	Aegirine crystals (high interference colors), orthose crystals (I order gray, with perthite unmixing) and quartz (I order gray). Gariboldi (or Kone) Caldera, Ethiopia. XPL image, 2x (Field of view = 7mm)	Aegirine (grass-green) and orthose crystals (colorless). Gariboldi (or Kone) Caldera, Ethiopia. PPL image, 2x (Field of view = 7mm)
Aegirine crystals (high interference colors), orthose crystals (I order gray, with perthite unmixing) and quartz (I order gray). Gariboldi (or Kone) Caldera, Ethiopia. XPL image, 2x (Field of view = 7mm)	Aegirine (grass-green) and orthose crystals (colorless). Gariboldi (or Kone) Caldera, Ethiopia. PPL image, 2x (Field of view = 7mm)	Aegirine crystals (high interference colors), orthose crystals (I order gray, with perthite unmixing) and quartz (I order gray). Gariboldi (or Kone) Caldera, Ethiopia. XPL image, 2x (Field of view = 7mm)
Aegirine (grass-green) and orthose crystals (colorless). Gariboldi (or Kone) Caldera, Ethiopia. PPL image, 2x (Field of view = 7mm)	Aegirine crystals (high interference colors), orthose crystals (I order gray, with perthite unmixing) and quartz (I order gray). Gariboldi (or Kone) Caldera, Ethiopia. XPL image, 2x (Field of view = 7mm)	Aegirine (grass-green) and orthose crystals (colorless). Gariboldi (or Kone) Caldera, Ethiopia. PPL image, 2x (Field of view = 7mm)
Aegirine crystals (high interference colors), orthose crystals (I order gray, with perthite unmixing) and quartz (I order gray). Gariboldi (or Kone) Caldera, Ethiopia. XPL image, 2x (Field of view = 7mm)	Aegirine crystals (high interference colors), orthose crystals (I order gray, with perthite unmixing) and quartz (I order gray). Gariboldi (or Kone) Caldera, Ethiopia. XPL image, 2x (Field of view = 7mm)	Aegirine crystals (high interference colors), orthose crystals (I order gray, with perthite unmixing) and quartz (I order gray). Gariboldi (or Kone) Caldera, Ethiopia. XPL image, 2x (Field of view = 7mm)
Aegirine crystals (high interference colors), orthose crystals (I order gray, with perthite unmixing) and quartz (I order gray). Gariboldi (or Kone) Caldera, Ethiopia. XPL image, 2x (Field of view = 7mm)	Aegirine crystals (high interference colors), orthose crystals (I order gray, with perthite unmixing) and quartz (I order gray). Gariboldi (or Kone) Caldera, Ethiopia. XPL image, 2x (Field of view = 7mm)	Aegirine crystals (high interference colors), orthose crystals (I order gray, with perthite unmixing) and quartz (I order gray). Gariboldi (or Kone) Caldera, Ethiopia. XPL image, 2x (Field of view = 7mm)
Aegirine (grass-green) crystals. Brandberg Complex (Namibia). PPL image, 2x (Field of view = 7mm)	Aegirine (high interference colors) crystals in a fine-grained matrix made of quartz and feldspar (I order gray). Brandberg Complex (Namibia). XPL image, 2x (Field of view = 7mm)	Aegirine (grass-green) crystals. Brandberg Complex (Namibia). PPL image, 2x (Field of view = 7mm)
Aegirine (grass-green) crystals and xenotime crystals (high relief). Brandberg Complex (Namibia). PPL image, 2x (Field of view = 7mm)	Aegirine (grass-green) crystals. Brandberg Complex (Namibia). PPL image, 2x (Field of view = 7mm)	Aegirine (high interference colors) crystals in a fine-grained matrix made of quartz and feldspar (I order gray). Brandberg Complex (Namibia). XPL image, 2x (Field of view = 7mm)
Aegirine (grass-green) crystals. Brandberg Complex (Namibia). PPL image, 2x (Field of view = 7mm)	Aegirine (high interference colors) crystals in a fine-grained matrix made of quartz and feldspar (I order gray). Brandberg Complex (Namibia). XPL image, 2x (Field of view = 7mm)	Aegirine (grass-green) crystals and xenotime crystals (high relief). Brandberg Complex (Namibia). PPL image, 2x (Field of view = 7mm)
Aegirine (grass-green) crystals. Brandberg Complex (Namibia). PPL image, 2x (Field of view = 7mm)	Aegirine (high interference colors) crystals in a fine-grained matrix made of quartz and feldspar (I order gray). Brandberg Complex (Namibia). XPL image, 2x (Field of view = 7mm)	Aegirine (high interference colors) crystals in a fine-grained matrix made of quartz and feldspar (I order gray). Brandberg Complex (Namibia). XPL image, 2x (Field of view = 7mm)
Xenotime (high interference colors) crystals in a fine-grained matrix made of quartz and feldspar (I order gray). Brandberg Complex (Namibia). XPL image, 10x (Field of view = 2mm)	Arfvedsonite crystals (blue). PPL image, 10x (Field of view = 2mm)	Xenotime (high relief) and arfvedsonite crystals (blue). PPL image, 10x (Field of view = 2mm)