Harzburgite's are a variety of peridotite and a major component of the upper mantle where they occur as xenoliths in mantle-derived magmas. They are an ultrabasic igneous rock dominated by olivine, and low calcium pyroxene. Harzburgite 's take their name from the Harz Mountains in Germany.
This one is from the world famous De Beer's mine in Kimberley, South Africa.


Polished slice, in a 2'x2' acrylic case, $28.00

Dunite is an igneous, ultramafic, plutonic rock with a coarse-grained texture. It is composed of more than 90% olivine with minor amounts of pyroxene, chromite, magnetite, and pyrope. It's a variety of peridotite and is one of the major constituents of the Earth's mantle. Dunite always contains some metallic minerals - chromite, magnetite and is a source of valuable ores and minerals, including platinum, nickel.
From the famous Robert Victor Mine, now called the Rovic Diamond Mine, in Free State Province, South Africa.
Polished slice, in a 2'x2' acrylic case, $28.00

Arfvedsonite in syenite.

Arfvedsonite in syenite.

The Wausau Intrusive complex is a Proterozoic group of plutons in Marathon County, Wisconsin.
Syenite is an igneous rock that cooled slowly in the Earth's crust similar to granite. Arfvedsonite is a rare sodium amphibole mineral that typically occurs as greenish black to bluish grey stellate prisms.
This specimen is from the Stettin complex of syenites and has arfvedsonite prisms in syenite in each sample.

Polished slice, in a 2'x2' acrylic case, $24.00

Vesicular Wyomingite Lamproite

Vesicular Wyomingite Lamproite

Vesicular Wyomingite is diopside, phlogopite, and lamproite from Leucite Hills.
Wyoming's Leucite Hills include a group of rare lamproitic volcanic flows containing unusual minerals - richterite, armalcolite, magesiochromite and noonkanbahite.


Polished slice, in a 2'x2' acrylic case, $28.00

Greenland Basalt

Greenland Basalt

The Scoresbysund area of southern Greenland has a varied geologic record that spans almost 3 billion years. This basalt is from the Blosseville Coast. A rifting process led to intense volcanism in this area 55 million years ago with large volumes of basalts covering most of southern Greenland. The basalts in this area are high in FeO and titanium dioxide.


Polished slice, in a 2'x2' acrylic case, $24.00

.Phonolite, Dunedin Volcano

.Phonolite, Dunedin Volcano

Phonolite is an uncommon extrusive, igneous, volcanic rock ranging in chemical composition between felsic and mafic. The textures are fine-grained to mixed (porphyritic). The name, derived from Greek meaning "sounding stone" is from the metallic sound it produces when struck. The English name is "clinkstone" From the Dunedin Volcano, an extinct shield volcano that last erupted around 10 million years ago.

Polished slice, in a 2'x2' acrylic case, $24.00

Zircon assemblage

Zircon

.Zircon

Zircons derived from alkali volcanoes generally show rounding from magmatic corrosion. Colors are typically orange-red to brown. Zircons are some of the oldest known, unaltered mineralogy on Earth with some dating to over 4.3 billion years. These zircon assemblages range from 10 to 15mm in size.


2 specimens in a 2'x2' acrylic case, $26.00

Eclogite, Israel

.Eclogite, Israel

Eclogites are high pressure, high temperature, coarse-grained metamorphic rock. They consist of pink-red garnet, and a sodium-rich variety of omphacite. They form when basalt or gabbro descend deeply into the Earth at subduction zones. At high pressure and temperatures the original minerals morph into the denser minerals granet and omphacite becoming eclogite. Because of their density, eclogites rarely return to the surface. This one is from southern Israel, the Negev Region.


Offered as a polished slice, in a 2'x2' acrylic case, $30.00

Reunion Island basalt

Reunion Island basalt

Reunion Island basalt

More basalt is in the Earth's crust than any other rock and ocean hotspots, such as Reunion Island (an overseas island of France), are primary locations for basalt to occur. This basalt is from one of the most active volcanoes on Earth, the shield volcano Piton de la Fournaise on the eastern end of the island. Since the 17th century, approximately 150 eruptions have occurred.

Offered in polished slices
Polished slice, in a 2'x2' acrylic case, $24.00

Phenocrystic Andesite

Phenocrystic Andesite

This is an extrusive igneous, volcanic rock with a porphyritic texture. It is intermediate between basalt and dacite. From the Hakone volcano in Honshu, Japan.

The Hakone volcano is a massive stratovolcano truncated by two huge overlapping calderas, each 11 x 10 km wide. A valley in one of the calderas with intense hydrothermal activity is called "Great Boiling Valley". The last magmatic eruption from Hakone was approximately 2900 years ago.

Offered in polished slices
Polished slice, in a 2'x2' acrylic case, $24.00

Sodalite replacing nepheline

Sodalite replacing Nepheline

Nepheline syenites are rare. They are distinguished from ordinary syenites not only by the presence of nepheline but also with the occurrence of many other alkali-rich minerals, rare earths, and other incompatible elements. Sodalite is a pale blue and the main feldspathoid mineral, in addition to nepheline, in syenites.
In this specimen of nepheline syenite from Mont St. Hilaire, Quebec, Canada, sodalite is replacing the nepheline.

Offered in polished slices
Polished slice, in a 2'x2' acrylic case, $28.00

Basalt, Milne Land formation, East Greenland

Basalt, Milne Land formation, East Greenland

The East Greenland Milne Land Formation basalts in the Prisen of Wales Bjerge are quite distinct in that they have high silicon dioxide and lower titanium dioxide/silicon dioxide ratios than other plateau basalts (Scoresbysund) in the area. This is convincing evidence that they do not belong to the Milne Land formation and it has been proposed that the Milne Land formation be divided into two new formal volcanic formations. This basalt is from the Prisen of Wales Bjerge.

Offered in polished slices
Polished slice, in a 2'x2' acrylic case, $28.00

Olivine basalt, Tahiti

Olivine basalt, Tahiti

There is more basalt in the Earth's crust than any other rock - and they are all different. This one, a basalt from the Papeete region of Tahiti, is rich in olivine phenocrysts - mineral grains of olivine substantially larger than the submillimeter grains normally seen in olivine basalts. The olivine sand found in island beeches is a disintegration product of olivine basalts.

Offered in polished slices.
Polished slice in a 2'x2' acrylic case, $28.00

Chromitic dunite

Chromitic dunite

The Beartooth Mountains of Montana's Stillwater Complex has one of only three platinum and palladium mines in North America. The rocks in this Complex are ultramafic & mafic intrusive igneous rocks. Common to the locality are gabbros, norites, harzburgites, chromitites, pyroxenites, and dunites. Chromitic dunites have a higher percentage of chromite than the norm.

Offered in polished slices
Polished slice, in a 2'x2' acrylic case, $29.00

Nepheline
Syenite, Uganda.

Nepheline
Syenite, Uganda.

This is a true, classic, nepheline syenite. It's a holocrystalline plutonic rock consisting of nepheline and alkali feldspar with coloring of grey or pink and in general appearance is similar to granites. Unlike granites though, there is no quartz and they're rich in rare earths elements.

Offered in polished slices
Polished slice, in a 2'x2' acrylic case, $28.00

Glomerolporphryitic basalt with Plagioclase phenocrysts

Glomerolporphryitic basalt with Plagioclase phenocrysts

Glomerolporphryitic basalt with Plagioclase phenocrysts

Glomerolporphyritic is a textural term used to describe igneous rocks that contain clusters of phenocrysts, which are large crystals in a finer-grained matrix or groundmass. This is a textbook example of the term; large, radiating plagioclase phenocrysts in basalt.

Offered in polished slices
Polished slices, in a 2'x2' acrylic case, $30.00

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Ultramafic xenolith, Mt. Carmel, Israel

Garnet, ultramafic xenolith, Mt. Carmel, Israel

Garnet ultramafic xenolith, Mt. Carmel, Israel

Volcanism in the Mt. Carmel region occurred early in the Late Cretaceous. Xenoliths from the Mt. Carmel area, Israel, are predominantly composed of high-Al clinopyroxene, pyrope-almandine garnet, spinel, and plagioclase.

Offered in polished slices
Polished slice, in a 2'x2' acrylic case, $28.00

An altered basalt, Denmark.