Monticellite - CaMgSiO4

Monticellite was discovered in 1831 and named by H.J.Brooke in honor of Teodoro Monticelli (1759-1845), Italian mineralogist and naturalist who published several works on Mount Vesuvius.
The structure of monticellite is essentially the same as that of the (Mg,Fe)-olivines, with an expanded unit cell due to the replacement of half of the (Mg,Fe) by Ca.

Monticellite is a calcic-olivine and forms a solid solution to kirschsteinite, the Fe-rich endmember; it occurs in two distinct parageneses: it is as common mineral developed during progressive metamorphism of siliceous and magnesian limestone, and in skarn zone at metasomatized limestone contacts with acid, alkaline and basic intrusions. Less frequently, monticellite occurs as costituent of ultrabasic rocks such as kimberlites, alnoites and carbonatites.

Optical Properties:

Form: As well-formed prismatic crystals; massive, granular.
Relief: Moderate.
Cleavage: Poor on 010.
Color: colorless in thin section.v • Twinning: Six-pointed star-shaped forms are common.
Interference colors: Low to moderate (gray-yellow-orange).




Bibliography



• Deer, W.A., Howie, R.A., Zussman, J. (1998) Rock-forming Minerals.
• Optical Mineralogy : The Nonopaque Minerals by Phillips / Griffen


Photo
monticellite(19).jpg

Calcite, small apatite crystals and monticellite (high relief, colorless and fractured) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. PPL image, 2x (Field of view = 7mm)
monticellite(20).jpg

Calcite, small apatite crystals (I order gray) and monticellite (I order yellow-orange) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. XPL image, 2x (Field of view = 7mm)
monticellite(21).jpg

Calcite, small apatite crystals and monticellite (high relief, colorless and fractured) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. PPL image, 2x (Field of view = 7mm)
monticellite(22).jpg

Calcite, small apatite crystals and monticellite (high relief, colorless and fractured) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. PPL image, 2x (Field of view = 7mm)
monticellite(23).jpg

Calcite, small apatite crystals (I order gray) and monticellite (I order yellow-orange) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. XPL image, 2x (Field of view = 7mm)
monticellite(24).jpg

Calcite, small apatite crystals (I order gray) and monticellite (I order yellow-orange) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. XPL image, 2x (Field of view = 7mm)
monticellite(25).jpg

Calcite, small apatite crystals and monticellite (high relief, colorless and fractured) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. PPL image, 2x (Field of view = 7mm)
monticellite(26).jpg

Calcite, small apatite crystals (I order gray) and monticellite (I order yellow-orange) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. XPL image, 2x (Field of view = 7mm)
monticellite(27).jpg

Calcite, small apatite crystals and monticellite (high relief, colorless and fractured) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. PPL image, 2x (Field of view = 7mm)
monticellite(28).jpg

Calcite, small apatite crystals (I order gray) and monticellite (I order yellow-orange) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. XPL image, 2x (Field of view = 7mm)
monticellite(30).jpg

Calcite, small apatite crystals and monticellite (high relief, colorless and fractured) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. PPL image, 2x (Field of view = 7mm)
monticellite(31).jpg

Calcite, small apatite crystals (I order gray) and monticellite (I order yellow-orange) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. XPL image, 2x (Field of view = 7mm)
monticellite(32).jpg

Calcite, small apatite crystals and monticellite (high relief, colorless and fractured) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. PPL image, 2x (Field of view = 7mm)
monticellite(33).jpg

Calcite, small apatite crystals (I order gray) and monticellite (I order yellow-orange) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. XPL image, 2x (Field of view = 7mm)
monticellite(34).jpg

Calcite, small apatite crystals and monticellite (high relief, colorless and fractured) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. PPL image, 2x (Field of view = 7mm)
monticellite(35).jpg

Calcite, small apatite crystals (I order gray) and monticellite (I order yellow-orange) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. XPL image, 2x (Field of view = 7mm)
monticellite(37).jpg

Calcite, small apatite crystals and monticellite (high relief, colorless and fractured) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. PPL image, 2x (Field of view = 7mm)
monticellite(38).jpg

Calcite, small apatite crystals (I order gray) and monticellite (I order yellow-orange) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. XPL image, 2x (Field of view = 7mm)
monticellite(41).jpg

Calcite, small apatite crystals and monticellite (high relief, colorless and fractured) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. PPL image, 10x (Field of view = 2mm)
monticellite(42).jpg

Calcite, small apatite crystals (I order gray) and monticellite (I order yellow-orange) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. XPL image, 10x (Field of view = 2mm)
monticellite(43).jpg

Calcite, magnetite (black), small apatite crystals and monticellite (high relief, colorless and fractured) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. PPL image, 10x (Field of view = 2mm)
monticellite(45).jpg

Calcite, small apatite crystals and monticellite (high relief, colorless and fractured) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. PPL image, 10x (Field of view = 2mm)
monticellite(46).jpg

Calcite, small apatite crystals (I order gray) and monticellite (I order yellow-orange) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. XPL image, 10x (Field of view = 2mm)
monticellite(47).jpg

Calcite, small apatite crystals and monticellite (high relief, colorless and fractured) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. PPL image, 10x (Field of view = 2mm)
monticellite(49).jpg

Calcite, small apatite crystals and monticellite (high relief, colorless and fractured) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. PPL image, 10x (Field of view = 2mm)
monticellite(50).jpg

Calcite, small apatite crystals (I order gray) and monticellite (I order yellow-orange) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. XPL image, 10x (Field of view = 2mm)
monticellite(51).jpg

Calcite, small apatite crystals (I order gray) and monticellite (I order yellow-orange) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. XPL image, 10x (Field of view = 2mm)
monticellite(54).jpg

Calcite, small apatite crystals (I order gray) and monticellite (I order yellow-orange) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. XPL image, 10x (Field of view = 2mm)
monticellite(55).jpg

Calcite, small apatite crystals and monticellite (high relief, colorless and fractured) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. PPL image, 10x (Field of view = 2mm)
monticellite(56).jpg

Calcite, small apatite crystals (I order gray) and monticellite (I order yellow-orange) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. XPL image, 10x (Field of view = 2mm)
monticellite(62).jpg

Calcite, small apatite crystals and monticellite (high relief, colorless and fractured) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. PPL image, 10x (Field of view = 2mm)
monticellite(63).jpg

Calcite, small apatite crystals (I order gray) and monticellite (I order yellow-orange) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. XPL image, 10x (Field of view = 2mm)
monticellite(64).jpg

Calcite, small apatite crystals (I order gray) and monticellite (I order yellow-orange) in a plutonic carbonatite (sövite) from Oka complex, Quebec, Canada. XPL image, 10x (Field of view = 2mm)