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Formula: Mg3Si2O5(OH)4
Phyllosilicate (sheet silicate),
serpentine subgroup
Crystal System: Trigonal
Specific gravity: 2.55 measured, 2.57 calculated
Hardness: 2½
Streak: White
Colour: Green, green blue, yellow, white.
Solubility: More easily decomposed by 1N hydrochloric acid than is
antigorite, sometimes unaffected by acids
Environment
Lizardite is perhaps the most common
serpentine mineral; lizardite
serpentinisation could occur at 76oC, which can
covert to antigorite at
greenschist facies conditions, but
antigorite and lizardite have been observed to co-exist over a
wide range of conditions. Serpentinisation of
dunite, peridotite
and ultramafic rocks is common. Lizardite can be found replacing
olivine in basalt, also as a
microscopic replacement in
amphibole and "uralite"
(pseudomorphs of
amphibole minerals, mainly
actinolite, after a
clinopyroxene mineral, mainly
augite).
Pseudomorphs of lizardite after
enstatite,
diopside/augite or
tremolite have been found, but thermal effects can convert
lizardite to antigorite or
talc + clinochlore. Many
lizardites form under oxidising retrograde conditions.
Associated minerals include other serpentines,
talc, chlorite,
magnetite -
magnesiochromite,
dolomite, magnesite and
brucite
(Dana)
Lizardite pseudomorphs after Chondrite -
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Alteration
See results for serpentine, which is a group of minerals including
antigorite,
chrysotile and lizardite, all of which share the same formula,
although
they have slightly different structures.
Back to Minerals