double chain and more complex inosilicates 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.

Note: Despite the videos being externally linked, depending on the speed of your internet connection, it could still take a minute or two for the full table to load.

To preview or play a video here at the featured thumbnail scale, click the gray play button (which turns blue when you hover over it). Move the cursor off the video and after a few seconds the play button will be hidden. The video can be paused and restarted by subsequent clicks. With some desktop browsers (for example, newer versions of Safari), a “picture-in-picture” option is available to view the videos at a larger scale; the picture-in-picture can be resized by dragging its corner. On desktop or laptop computers, if you’ve selected a video and prefer to watch it full-screen, a full screen button should be available, but in some browsers the button may be hidden. In the latter case, right-click (PC) or control-click (Mac) and select “open frame in new window (or new tab)” from the menu. You’ll initially get a “Sorry, because of its privacy settings, this video cannot be played here” error message, but you’ll also get access to the blue “view on Vimeo” button, which will lead you to where the video is hosted on Vimeo and where you’ll get a variety of viewing and sharing options. On tablets and phones, videos should play in full screen mode by default. On some desktop browsers as well, the thumbnails may also expand to play full screen, for example after a subsequent “play” click of the video.

The Vimeo-hosted versions of these video are also search-engine discoverable, and can be found by searching for the term “thin section” coupled with the sample number (e.g. “thin section FKM-49”), with or without also including the accompanying mineral name. YouTube-hosted versions of these videos are no longer search-engine discoverable (in protest of YouTube polluting even short educational videos with non-optional ads… grrr!), but can still be found organized in playlists on my rockPTX YouTube channel.


mineral PPL (lower
polar rotation)
(stage rotation)
(stage rotation)
optic figure
(stage rotation)
anthophyllite (FKM-186):
anthophyllite amphibole in meta-blackwall, with phlogopite
(FKM-190): proto-ferro-suenoite (3.14 to 3.91 VIFe2+ apfu; 1.58 to 1.87 VIIIMn2+ apfu) amphibole (formerly “proto-mangano-ferro-anthophyllite”) in high grade meta-Mn-metasomatite, with rhodochrosite, quartz, spessartine garnet and pyroxmangite
clino-suenoite (FKM-122):
anomalously B(-) clino-suenoite (4.91 VIMg apfu; 1.25 VIIIMn2+ apfu) amphibole (formerly “tirodite” or “manganocummingtonite”) in Mn-rich pod in granulite facies metasomatized meta-evaporite, with donpeacorite orthopyroxene
(FKM-94): clino-ferro-suenoite (3.08 VIFe2+ apfu; 1.34 VIIIMn2+ apfu) amphibole (formerly “dannemorite” or “manganogrunerite”) in granulite facies metasomatized-Mn-Zn-Pb exhalite, with Fe-bearing pyroxmangite and Fe-bearing spessartine garnet
“sodic-gedrite” (FKM-11):
“sodic-gedrite” (0.58 XIINa apfu) amphibole in granulite facies meta-blackwall, with sapphirine and phlogopite mica
tremolite (FKM-26):
V-bearing (0.31 V apfu) tremolite-magnesio-hornblende near-boundary composition amphibole in high grade calc-silicate, with calcite, quartz and diopside clinopyroxene
tremolite (FKM-123):
lilac tremolite (“hexagonite”) amphibole in high grade calcareous meta-evaporite
tremolite (FKM-276):
Cr-bearing tremolite (0.03 to 0.06 Cr apfu) amphibole in granulite facies metasomatic calcareous meta-evaporite, with quartz and oxy-chromium-dravite tourmaline
actinolite (FKM-95):
actinolite (2.36 Fe2+ apfu) amphibole in greenschist facies meta-BIF, with magnetite, quartz and calcite
(FKM-161): Mn-bearing magnesio-hornblende (3.86 VIMg apfu; 0.23 VIIIMn2+ apfu) amphibole in amphibolite facies Ca-metasomatite, with quartz
tschermakite (FKM-24):
tschermakite (2.97 VIMg apfu; 1.04 VIAl apfu; 0.94 Fe3+ apfu) amphibole in high grade amphibolite, with anorthite plagioclase feldspar
pargasite (FKM-11):
pargasite amphibole in granulite facies meta-blackwall, with sapphirine and “sodic-gedrite” amphibole
pargasite (FKM-16):
pargasite (4.06 Mg apfu) amphibole in metasomatic amphibolite, with chrysoberyl
pargasite (FKM-68):
Cr-bearing pargasite (0.07 Cr apfu) amphibole in high grade meta-gabbroid, with zoisite and corundum
pargasite (FKM-290):
Cr-bearing pargasite (0.13 Cr apfu amphibole in high grade meta-gabbroid, with epidote, clinochlore chlorite, Cr-bearing spinel and zoisite
mangani-pargasite (FKM-387):
mangani-pargasite amphibole in Mn metasomatite, with calcite and hausmannite
(FKM-96): potassian magnesio-hastingsite (0.32 K apfu; 2.22 VIMg apfu; 0.80 Fe3+ apfu; 0.38 Ti apfu) amphibole in granulite facies meta-tonalite, with plagioclase
(FKM-264): magnesio-hastingsite (3.70 VIMg apfu; 0.75 Fe3+ apfu) amphibole in alkaline ultramafic intrusive, with calcite
(FKM-265): magnesio-hastingsite (3.47 to 3.80 VIMg apfu; 0.71 Fe3+ apfu; 0.02 Cr apfu) amphibole in alkaline ultramafic intrusive, with calcite and diopside
(FKM-21): potassic-magnesio-hastingsite amphibole in K-Cl-Fe metasomatite, with magnetite
hastingsite (FKM-33):
K- and Cl-bearing (0.39 K apfu; 0.26 Cl apfu) hastingsite amphibole in high grade K-Cl-Fe metasomatite, with biotite mica
ferri-kaersutite (FKM-49):
zoned ferri-kaersutite (yellow/brown core) to magnesio-hastingsite (yellow/green rim) amphibole in nepheline syenite, with clinopyroxene, apatite, titanite, plagioclase and an opaque oxide
ferri-kaersutite (FKM-251):
potassian ferri-kaersutite amphibole in essexite, with biotite, apatite, titanite, plagioclase and nepheline
winchite (FKM-74):
zoned winchite-richterite-actinolite near-boundary composition amphibole in carbonatite-associated K-metasomatite, with diopside clinopyroxene, microcline K-feldspar and calcite
barroisite (FKM-34):
zoned barroisite to taramite amphibole in eclogite facies metabasite, with garnet, rutile, quartz and zoisite
fluoro-richterite (FKM-27):
fluoro-richterite amphibole in metamorposed agpaitic syenite, with eudialyte, K-feldspar, aegirine clinopyroxene and fluorite
fluoro-richterite (FKM-65):
fluoro-richterite amphibole in metamorposed agpaitic syenite, with alkali feldspar
(FKM-249): ferro-ferri-katophorite to near boundary composition ferro-ferri-taramite amphibole in miaskitic nepheline syenite, with aegirine-augite clinopyroxene, alkali feldspar and nepheline
(FKM-305): ferro-ferri-fluoro-katophorite (0.94 F apfu; ~3.52 CFeT apfu) amphibole in alkali feldspar microsyenite, with Na-sanidine (K-feldspar)
hjalmarite (FKM-299):
Mn+Fe-bearing (0.67 B[Mn2++Ca] apfu with 0.47 BMn2+ apfu; 0.78 CMn2+ apfu; 0.65 CFe2+ apfu; preceding values based on ∑Si=8) hjalmarite amphibole in meta-Mn-metasomatite, with quartz, rhodonite and yoshimuraite
glaucophane (FKM-3):
glaucophane amphibole in blueschist, with jadeite clinopyroxene
glaucophane (FKM-100):
glaucophane amphibole in blueschist, with epidote, phengite mica and quartz
glaucophane (FKM-194):
glaucophane amphibole in siliceous blueschist, with quartz
riebeckite (FKM-139):
riebeckite amphibole in peralkaline granite pegmatite, with quartz, microcline and white mica
eckermannite (FKM-84):
variably Cr-enriched eckermannite amphibole in blueschist facies metamorphosed albitite, with Cr-jadeite and kosmochlor clinopyroxene and chlorite
(FKM-320): potassic-arfvedsonite amphibole in nepheline syenite
(FKM-145): zoned magnesio-fluoro-arfvedsonite to fluoro-leakeite amphibole in agpaitic nepheline syenite, with aegirine clinopyroxene and fine-grained unidentified groundmass
(FKM-39): zoned potassic-magnesio-arfvedsonite (core) to potassic-richterite (rim) amphibole in fenite-like K-metasomatite, with charoite and K-feldspar
holmquistite (FKM-164):
holmquistite amphibole in granite-adjacent Li-metasomatized wallrock, with quartz, chlorite and tourmaline
holmquistite (FKM-380):
holmquistite amphibole in granite-adjacent Li-metasomatized black-wall, with quartz, and biotite
fluoro-leakeite (FKM-175):
presumed fluoro-leakeite (Li analysis pending) in agpaitic nepheline syenite, with aegirine clinopyroxene, nepheline and alkali feldspar
ferri-fluoro-leakeite (FKM-256):
ferri-fluoro-leakeite in albitized granite, with aegirine-augite, quartz and alkali feldspar (100X)
(FKM-30): zoned mangano-mangani-ungarettiite to potassic-mangano-mangani-ungarettiite amphibole in meta-Mn-metasomatite, with serandite and quartz
inesite (FKM-76):
inesite in hydrothermal Mn-rich quartz-carbonate vein, with quartz and calcite
tinaksite (FKM-39b):
tinaksite in fenite-like K-metasomatite, with charoite
astrophyllite (FKM-227):
astrophyllite in nepheline syenite, with plagioclase and aegirine clinopyroxene
serendibite (FKM-135):
serendibite in calc-silicate high grade B-bearing Mg-calc-silicate, with tourmaline, phlogopite mica and calcite
serendibite (FKM-295):
serendibite in high grade B-bearing skarn, with diopside clinopyroxene
sapphirine (FKM-11):
sapphirine (0.43 FeT apfu) in granulite facies meta-blackwall, with phlogopite mica
sapphirine (FKM-23):
sapphirine (up to 2.26 FeT apfu) in granulite facies metapelite, with cordierite, sillimanite, garnet and rutile
neptunite (FKM-244):
neptunite in serpentine-hosted natrolite veins, with benitoite and natrolite(?)

non-silicates in thin section

nesosilicates in thin section

sorosilicates and cyclosilicates in thin section

single chain inosilicates in thin section

phyllosilicates in thin section

tectosilicates and miscellaneous silicates in thin section