Editing Serpentinization (section)

===Metamorphism at higher pressure and temperature===
Lizardite and chrysotile are stable at low temperatures and pressures, while antigorite is stable at higher temperatures and pressure.<ref>{{Cite journal |last=Evans |first=Bernard W. |date=2004-06-01 |title=The Serpentinite Multisystem Revisited: Chrysotile Is Metastable |journal=International Geology Review |volume=46 |issue=6 |pages=479–506 |doi=10.2747/0020-6814.46.6.479 |bibcode=2004IGRv...46..479E |s2cid=98271088 |issn=0020-6814}}</ref> Its presence in a serpentinite indicates either that serpentinization took place at unusually high pressure and temperature or that the rock experienced higher grade metamorphism after serpentinization was complete.<ref name="Moody1976" />

Infiltration of {{CO2}}-bearing fluids into serpentinite causes distinctive ''[[Talc carbonate|talc-carbonate alteration]]''.<ref>{{cite journal |last1=Naldrett |first1=A. J. |title=Tale-Carbonate Alteration of some Serpentinized Ultramafic Rocks south of Timmins, Ontario |journal=Journal of Petrology |date=1 October 1966 |volume=7 |issue=3 |pages=489–499 |doi=10.1093/petrology/7.3.489}}</ref> Brucite rapidly converts to [[magnesite]] and serpentine minerals (other than antigorite) are converted to talc. The presence of [[pseudomorph]]s of the original serpentinite minerals shows that this alteration takes place after serpentinization.<ref name="Moody1976" />

Serpentinite may contain [[chlorite group|chlorite]] (a [[phyllosilicate]] mineral), [[tremolite]] (Ca<sub>2</sub>(Mg<sub>5.0-4.5</sub>Fe<sup>2+</sup><sub>0.0-0.5</sub>)Si<sub>8</sub>O<sub>22</sub>(OH)<sub>2</sub>), and metamorphic olivine and [[diopside]] (calcium-rich pyroxene). This indicates that the serpentinite has been subject to more intense metamorphism, reaching the upper [[greenschist]] or [[amphibolite]] [[metamorphic facies]].<ref name="Moody1976" />

Above about {{convert|450|C||sp=us}}, antigorite begins to break down. Thus serpentinite does not exist at higher metamorphic facies.<ref name=FruhGreenEtal2004/>