tectosilicates and miscellaneous silicates in thin section

 

Check out the video atlas of minerals in thin section introduction page for some background on how these videos were prepared and processed, and for additional useful information on the included table content, the search tab, and other user-adjustable features. There is also an accompanying illustration to assist viewers with determining 2V° values from the BxA or optic axis figures in the “optic figures” videos.

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mineral PPL (lower
polar rotation)
PPL
(stage rotation)
XP
(stage rotation)
optic figure
(stage rotation)
quartz (FKM-15):
quartz in blueschist facies ferruginous meta-quartzite, with spessartine garnet
sanidine (FKM-80):
sanidine (K-feldspar) in haüyne phonolite, with aegirine clinopyroxene
orthoclase (FKM-78):
orthoclase micro-mesoperthite in high grade low-silica feldspathic gneiss, with biotite
microcline (FKM-74):
microcline K-feldspar in carbonatite-associated K-metasomatite, with diopside clinopyroxene, zoned amphibole and apatite
microcline (FKM-315):
microcline in metamorposed agpaitic syenite, with omphacite/aegirine-augite clinopyroxene and mosandrite-(Ce)
old video with especially distracting stray polarization effects scheduled to be replaced
anorthite (FKM-24):
anorthite (An95) plagioclase feldspar in high grade amphibolite, with tschermakite amphibole
reedmergnerite (FKM-52):
reedmergnerite feldspar in highly fractionated alkali granite, with quartz
nepheline (FKM-77):
anomalously slightly biaxial nepheline in kakortokite, with albite plagioclase and eudialyte
nepheline (FKM-120):
nepheline in miaskitic nepheline syenite, with alkali feldspar, cancrinite and calcite
nepheline (FKM-146):
anomalously slightly biaxial nepheline in agpaitic nepheline syenite (“lakarpite”), with arfvedsonite amphibole and apatite
nepheline (FKM-218):
nepheline in leucite nephelinite, with diopside clinopyroxene and leucite
kalsilite (FKM-271):
slightly altered Fe3+-bearing (0.29 to 0.40 Fe3+ apfu per ∑T=4.00) kalsilite in pyrometamorphic sanidinite facies phosphatic metacarbonate, with andradite garnet, gehlenite melilite, wollastonite and apatite (note: thin section is slightly thick)
leucite (FKM-218):
anomalously biaxial leucite in leucite nephelinite, with diopside clinopyroxene and nepheline
nosean (FKM-7):
nosean in nosean phonolite
isotropic
haüyne (FKM-313):
haüyne in haüyne tephritic phonolite, with Na-sanidine (K-feldspar), plagioclase and diopside clinopyroxene
isotropic
lazurite (FKM-25):
lazurite in granulite facies calcareous meta-evaporite, with calcite, phlogopite, diopside and nepheline (note: thin section is cut substantially thin)
isotropic (minor birefringent areas may be admixture with non-isometric polymorphs)
genthelvite (FKM-282):
genthelvite in granite, with albite, orthoclase and biotite
isotropic
cancrinite (FKM-120):
camcrinite in miaskitic nepheline syenite, with plagioclase, nepheline and calcite
meionite (FKM-165):
meionite (“wernerite”; 1.90 Na apfu; 1.84 Ca apfu) scapolite in crustal “carbonatite”, with calcite and titanite
ussingite (FKM-60):
ussingite in late pegmatite in agpaitic syenite
stilbite (FKM-170):
stilbite in zeolite facies altered basalt

non-silicates in thin section

nesosilicates in thin section

sorosilicates and cyclosilicates in thin section

single chain inosilicates in thin section

double chain and more complex inosilicates in thin section

phyllosilicates in thin section