Sean David

Garnetite enclave in garnet clinpyroxenite mantle xenolith
Oʻahu, Hawaiʻi

#pyroxenite #geology #xenolith #hawaii #volcanology #garnet #garnetite #geoscience

Garnetite enclave in garnet clinopyroxenite mantle xenolith
Oʻahu, Hawaiʻi

#pyroxenite #geology #xenolith #hawaii #volcanology #garnet #garnetite #geoscience

Dunite and troctolite xenoliths hosted by hawaiitevand closeup of dunite olivines
Laupāhoehoe Volcanics, Mauna kea

#geology #geoscience #volcano #hawaii #maunakea #xenolith #peridotite #dunite #troctolite #olivine

Kailua Member of the Koʻolau Basalt
Secondary minerals including opal, cristobalite, and epidotized plagioclase glomerocrysts

#geology #geoscience #hawaii #metamorphism #epidote #plagioclase #quartz #Basalt #opal

Select olivine sands (one ʻōmaʻo) formed from olivine weathered out of tuffs of Honolulu Volcanics tuff rings and cones on Oʻahu.

#geology #geoscience #sand #olivine #mineral #hawaii #olivinesand

Garnetite enclave in garnet pyroxenite mantle xenolith
Oʻahu, Hawaiʻi

#pyroxenite #geology #xenolith #hawaii #volcanology #garnet #garnetite #geoscience

Plagioclase and spinel peridotites of mantle and crustal origin hosted by basanite

One of the three Nuʻuanu flows (~600 ka), Honolulu Volcanics, Koʻolau,

#peridotite #xenolith #geology #geoscience #volcano #Hawaii

I'm back in Hawaiʻi
And here is a titaniferous #augite glomerocryst with #olivine ingrowths

Koko Rift, #Honolulu #Volcanics
#Oʻahu, #Hawaiʻi

#geoscience #clinopyroxene #mineral #titanaugite #geology

Chrome diopside vein in peridotite mantle xenolith.

San Carlos Volcanic Field, San Carlos Apache Reservation, Arizona

#peridotite #xenolith #lherzolite #geology #geoscience #chromediopside #pyroxene #clinopyroxene #Volcano

Harzburgite
Blue Ridge Ophiolite, North Carolina
From a now inactive extremely slow-moving spreading center.

#geology #geoscience #peridotite #harzburgite #olivine #orthopyroxene #mantle #Ophiolite

Is this xenolith an orthopyroxene-bearing troctolite or a plagioclase-bearing olivine websterite? 😭 I'll have to not forgot my loupe again when back in January.

Kaʻūpūlehu Flow Field, Hualālai Volcanics, Hualālai, Hawaiʻi

#xenolith #mafic #ultramafic #troctolite #websterite #geoscience #geology

Revisiting this Honolulu Volcanics mantle xenolith which has a porphyroclastic texture. Note the bimodal grain size distribution of the olivines with large subhedral porphyroclasts and smaller relatively euhedral neoblasts in the matrix.

#xenolith #peridotite #geology ##geoscience #olivine

Dianella?

Dunite xenoliths in picrite, Koʻolau. Due to their high density and low viscosity, picrites are the only tholeiitic melts that can carry ultramafic xenoliths to the surface. In Hawaiʻi, these are usually crustal cumulates of tholeiitic affinity.

#xenolith #dunite #geology #geoscience #picrite

Back on Oʻahu and Big Island in late January and super excited to get to (re)visit mantle and crustal xenoliths of the Koʻolau Honolulu Volcanics as well as those of Hualālai, Mauna Kea, and unusual Mauna Loa ultramafic mantle xenoliths hosted by tholeiitic basalt.

#xenolith #peridotite #geology

Extrapolating on heavily argillized rhyolites cut by pebble and andesite dikes.

Packard Quartz Latite (35.27 ± 0.03 ma)
East Tintic Mountains, Utah

#geology #geoscience #rhyolite #pebbledikes

Kilbourne Hole peridotite mantle xenolith with area of dark orthopyroxene crystals formed via the rock-melt reaction MG2Si04 + Si02 → 2MgSi03. Part of a complex history involving rock-melt interaction, refertilization, and multiple metasomatic events.

#xenolith #peridotite #pyroxene #orthopyroxene

Metasomatism is one of my least favorite things, but at least the classic propylitic alteration mineral assemblage involving chloritization and epidotization yields a rather aesthetic look.

(Quartz?) monzonite
Silver City Stock (Oligocene)
Tintic Mountains,Utah
#metasomatism #geology #geoscience

Towards the edge of a possible caldera

Twin Peaks Subfield, Black Rock Desert Volcanic Field, Utah

#Obsidian #rhyolite #volcanism #geology #geoscience #volcanicglass

Some silica-rich eruptive products of the Twin Peaks Subfield, Black Rock Desert Volcanic Field, Utah

#Obsidian #rhyolite #volcanism #geology #geoscience #volcanicglass

Mahogany + snowflake obsidian

Twin Peaks Subfield, Black Rock Desert Volcanic Field, Utah

#Obsidian #rhyolite #volcanism #geology #geoscience #volcanicglass

Retrograde eclogite imprinted with blueschist facies minerals including phengite (golden flakey mineral), actinolite (black needles), and glaucophane (blue).

Franciscan Complex, California

#eclogite #blueschist #metamorphism #geology #geoscience #glaucophane #mica #amphibole

Oligocene rhyolite cut by andesite and pebble dikes. Extensive argillization and limonite staining. Initially identified as a quartz latite, the Packard Quartz Latite (35.27 ± 0.03 ma) plots as a subalkaline rhyolite.

East Tintic Mountains, Utah

#geology #geoscience #rhyolite #pebbledikes

Twinned topaz.
Thomas Mountains, Utah

#topaz #geology #geoscience #rhyolite #mineral #utah

Topaz
Sherry colored freshly collected crystals and one in matrix that has been exposed to the sun.
Thomas Mountains, Utah

#topaz #geology #geoscience #rhyolite #mineral #utah

So excited to be back here in a week!

Topaz
Thomas Mountains, Utah

#topaz #geology #geoscience #rhyolite #mineral

Spinel lherzolite mantle xenolith hosted by phonotephrite (collected with permission)

San Carlos Volcanic Field, San Carlos Apache Reservation, Arizona

#peridotite #xenolith #lherzolite #geology #geoscience #volcano

In things that make me happy, a bit of the collection...Lawsonite blueschist, eclogitic blueschist, glaucophanite, various eclogites, orthopyroxenite, clinopyroxenite, garnet websterite

#eclogite #pyroxenite #blueschist #clinopyroxenite #websterite #garnet #metamorphic #geology #geoscience

Olivine is my second fav mineral after pyropic garnet and am super loving this forsteritic olivine ring. Peridotite xenolith in phonotephrite is from the classic location of the San Carlos volcanic field.

#olivine #xenolith #peridotite

My hometown in the Koʻolau Caldera. Kailua Member of the Koʻolau Basalt and a dike of (likely) basaltic andesite. Reference location is super close to here. I recieved a grant that will cover next semester (that unfortunately has to be spent at a Utah university) but would rather be back here.