Rhyodacite
Hand Sample: Aphanitic, pink-black rhyodacite. Sample contains alternating black and dark pink bands across face. Sample does not contain any vesicles or phenocrysts.
Thin Section: Groundmass is microcrystalline, with abundant phenocrysts of plagioclase, olivine, and pyroxenes.
Sample collected in January, 1969.
Western Minerals
HA-31
Melilite Nephelinite
Hand Sample: Aphanitic light gray nephelinite containing some melilite. Melilite is the white minerals that range in size from 0.1 to 0.5cm. Sample contains numerous small sized (less than 0.05cm) vesicles that are evident on the cut face.
Thin Section: Groundmass composed of euhedral quartz grains with abundant phenocrysts of olivine and pyroxenes.
Sample collected in January, 1969.
Western Minerals
HA-30
Nephelinite
Hand Sample: Aphanitic medium gray nephlenite. White intergrowth crystals are common throughout the sample and form long strands (approx. 0.6 - 1cm in length) on sides of sample. Sample contains some melilite.
Thin Section: Groundmass is primarily glass and pyroxenes. Phenocrysts of pyroxenes and olivine are present throughout the sample.
Sample collected in January, 1969.
Western Minerals
HA-29
Alkalic Olivine Basalt
Hand Sample: Aphanitic dark gray vesicular basalt. Vesicles are common throughout sample and range in size from 0.1 to 3.5cm in diameter. Individual olivine crystals are found throughout the sample and range in size from 0.1 to 0.4cm in length.
Thin Section: Groundmass dominated by plagioclase, glass and pyroxenes. Large phenocrysts of euhedral to subhedral olivine can be observed throughout the sample in addition to occasional vesicles.
Sample collected in January, 1969.
Western Minerals
HA-28
Alkalic Olivine Basalt
Hand Sample: Aphanitic dark gray vesicular basalt. Sample contains numerous vesicles ranging in size from less than 0.05cm to 1.5cm. Individual olivine crystals can also be found throughout the sample.
Thin Section: Groundmass of medium size plagioclase, pyroxenes, and olivine. Vesicles are numerous throughout the sample.
Sample collected in January, 1969.
Western Minerals
HA-27
Scoria
Hand Sample: Microcrystalline vesicular, dark-gray to black scoria. Vesicle size varies throughout the sample, ranging from larger circular vesicles with a diameter of approx. 1.5 cm on one surface and small vesicles (less than 0.1cm in diameter) on the opposite face. Sample has low specific gravity due to abundance of vesicles.
Thin Section : Groundmass composed of glass and microcrystaline grains of plagioclase. Large elongated vesicles are observed throughout the thin section.
Sample collected in January, 1969.
Western Minerals
HA-26
Peridotite/Dunite
Hand Sample: Natural surface of sample is dark in color with smooth texture. Cut face reveals blocks of peridotite and dunite held together with a thin layer of lava cement. Sample has high specific gravity.
Thin Section: Large euhedral to subhedral olivine grains compose the majority of the sample, with thin bands of glass material between them.
Sample collected in January, 1969.
Western Minerals
HA-25
Lapilli Tuff
Hand Sample: Lapilli tuff containing pieces of pumice (HA-23) and trachyte obsidian (HA-22) ranging in size from 0.1cm to 1.5cm. Clasts are held together in light-colored ash. Sample surface crumbles when handled. Lapilli describes the size of the clasts, indicating a range in diameter of approx. 2 to 64mm.
Thin Section: Groundmass is predominantly clasts of pumice and trachyte obsidian, which are composed of glass and plagioclase grains in a glass matrix material.
Western Minerals
HA-24
Pumice
Hand Sample: Aphanitic light gray vesicular pumice. Sample has incredibly low specific gravity due to abundant vesicles. Vesicles range in size from less than 0.1cm to 0.3cm. Some vesicles on cut face appear to be filled in with a lighter material. Sample contains blocks of Trachyte Obsidian from sample HA-22.
Thin Section: Groundmass composed of aphanitic glass, opaque minerals, and some plagiocalse. Numerous vesicles are present.
Sample collected in January, 1969.
Western Minerals
HA-23
Trachyte Obsidian
Hand Sample: Aphanitic dark gray trachyte. Sample contains zones with abundant tiny vesicles (less than 0.1cm in diameter), however the majority of the sample does not contain any vesicles or phenocrysts.
Thin Section: Composed of aphanitic plagioclase grains displaying characteristic twinning in addition to a large amount of glass.
Sample collected in January, 1969.
Western Minerals
HA-22
Alkalic Olivine Basalt
Hand Sample: Aphanitic light gray vesicular basalt with large olivine crystals. Olivine phenocrysts range in size from single crystals approx. 0.1cm in diameter to clusters of olivine as large as 1cm in diameter. Vesicles throughout the sample are primarily large and also elongate in shape.
Thin Section: Groundmass composed of small sized plagioclase grains, glass, and clinopyroxene. Some small phenocrysts of olivine present throughout the thin section.
Sample collected in January, 1969.
Western Minerals
HA-21
Hawaiite
Hand Sample: Aphanitic light gray hawaiite. Sample contains sparse vesicles that are generally 0.1cm or less in diameter.
Thin Section: Composed primarily of medium size plagioclase crystals with some microcrystals of pyroxene.
Sample collected in January, 1969.
Western Minerals
HA-20
Ankaramite
Ankaramites are dark porphyritic basalts that contain abundant pyroxene and olivine phenocrysts. Lesser amounts of biotite, and plagioclase may also be present.
Hand Sample: Aphanitic dark gray vesicular Ankaramite. Sample contains abundant vesicles ranging in size from less than 0.05cm to 0.8cm. Sample also contains numerous larger crystals with iridescent luster ranging in size from 0.1cm to 0.8cm. Phenocrysts of olivine approximately 0.2cm in diameter can also be found throughout the sample.
Thin Section: Groundmass made up of microcrystals of clinopyroxenes, glass, plagioclase. Phenocrysts of olivine and pyroxenes are present in addition to some accessory biotite grains.
Sample collected in January, 1969.
Western Minerals
HA-19
Trachyte
Trachytes are an igneous volcanic rock with an aphanitic or porphyritic texture. Alkali feldspar, low amounts of plagioclase and quartz or a feldspathoid are common in trachytes.
Hand Sample: Aphanitic, light gray trachyte. On cut face, inclusions ranging from 0.8cm to 2cm in length with abundant vesicles less than 0.05cm in diameter can be observed.
Thin Section: Composed nearly entirely of glass material with some subhedral to euhedral plagioclase crystals that vary in size.
Sample collected January, 1969
Western Minerals
HA-18
Tholeiitic Basalt
Hand Sample: Aphanitic dark gray vesicular basalt. The vesicles are uniform and common throughout the sample, with diameters of approx. 0.05 cm.
Thin Section: Groundmass consists of medium size plagioclase with small crystals of pyroxenes. The sample is uniform, with no large phenocrysts. Vesicles (~0.03mm) are present in sample.
Sample collected January, 1969
Western Minerals
HA-17
Oceanite
Hand Sample: Aphanitic dark gray vesicular basalt with olivine crystals scattered throughout. The olivine crystals are most common in this sample than in other samples within the suite. Sample was collected from an olivine-rich zone within Mauna Loa flow.
Thin Section: Groundmass composed of mainly of glass, plagioclase, microcrystals of clinopyroxene. Thin section also contains phenocrysts of olivine and pyroxene.
Sample collected January, 1969
Western Minerals
HA-16
Clinkery aa
Hand Sample: Apahanitic, vesicular, dark gray-black basalt. Olivine crystals are scattered throughout the sample and are approx. 0.05cm in diameter. Vesicles are very predominant throughout the sample and range in diameter from 0.01 cm to 1.5 cm This sample displays characteristics of rough aa texture. The surface of the rock is dark red-brown likely due to weathering.
Thin Section: Aphanitic groundmass composed of mainly glass and microcrystals of clinopyroxene. Medium size, elongated, euhederal plagioclase crystals are present that display twinning.
Sample collected January, 1969
Western Minerals
HA-15
Tholeiitic Basalt
Hand Sample: Aphanitic medium gray vesicular basalt with scattered olivine crystals. Olivine crystals are commonly growing either in clusters or as one single crystal. Vesicles are found throughout sample and range in diameter from 0.05cm to 2cm.
Thin Section: Groundmass composed of plagioclase grains and glass. Sample contains plagioclase phenocrysts with elongate shape as well as numerous olivine phenocrysts.
Sample collected January, 1969
Western Minerals
HA-14
Tholeiitic Basalt
Hand Sample: Aphanitic dark gray vesicular basalt. Basalt has ropey pahoehoe texture on top surface and contains numerous elongated vesicles.
Thin Section: Groundmass of glass, plagioclase and microcrystals of clinopyroxenes. The plagioclase crystals are elongated in shape and the clinopyroxenes have a block like shape. Numerous vesicles are present in the thin section.
Sample collected January, 1969
Western Minerals
HA-13
Tholeiitic Basalt
Hand Sample: Aphanitic vesicular dark gray-black basalt with larger light crystals throughout the sample. The vesicles throughout the sample are elongate in shape, and range in size from 0.5 cm to 2.5 cm. Sample surface displays rough AA texture.
Thin Section: Groundmass of plagioclase, interstitial glass, and microcrystals of clinopyroxenes. In the picture, there is a large plagioclase phenocryst.
Sample collected January, 1969
Western Minerals
HA-12