There is a stunning mix of clasts within this sample of kimberlite from the DeBeers, Premier Mine, in South Africa. The Premier Diamond Mine is geologically, the oldest known kimberlite pipe. Every sample is diverse in its presentation.

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

Eclogites are dramatic, intense-looking rocks from the Earth's upper mantle. This is a great one from Marin County, California with lots of amber colored garnet throughout. They are of special interest because they form at pressures greater than those typical of the crust of the Earth and being an unusually dense rock, eclogites play an important role in driving convection within the upper mantle. This fresh rock is striking in appearance, with orange garnet in a green matrix of sodium-rich pyroxene (omphacite). Accessory minerals include kyanite, rutile, quartz, lawsonite, coesite, amphibole, phengite, paragonite, zoisite, dolomite, corundum, and, sometimes, diamond!.

Offered in polished slices.
Polished slices, in a 2'x2' plastic case, $32.00

Pyroclastic Kimberlite, Canada,. in thin section

Pyroclastic Kimberlite, Canada

Pyroclastic Kimberlite, Canada

Pyroclastic rocks are formed by explosive eruption of lava and any rocks which are entrained within the eruptive column. This may include rocks pulled off the wall of the magma conduit, or physically picked up by the ensuing pyroclastic surge. The resulting rock is a volcanic breccia.

All specimens of pyroclastic kimberlite are best seen in prepared slices. They are all clast-filled and different with both angular and rounded clasts well consolidated into the matrix and visually intense in thin section.These samples are from the Lac de Gras Province, NWT, Canada.

Offered in polished slices.
Polished slices, in a 2'x2' plastic case, $32.00

Carbonatite with zirconolite and calzirtite

Carbonatite with zirconolite and calzirtite

Carbonatite with zirconolite and calzirtite

This is a porphyritic carbonatite dyke rock from the Kaiserstuhl, the largest volcanic center in the Rhine Graben. There's a lot of great mineralogy in this one. Phonolites and extrusive carbonatites are present along with Mn-rich olivine, pyrochlore, Nb-rich perovskite, baddelyite, and the rare minerals zirconolite and calzirtite as Nb-rich varities with REE!

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

Spinel Lherzolite xenolith in thin section

Spinel Lherzolite xenolith

Spinel Lherzolite xenolith

This specimen is from the Yuzhnoe multi-phase, intrusive body (late Jurassic, 145 Ma), of the Lambert-Amery Rift System (Jetty Peninsula, East Antarctica. It is a slightly serpentized rock delivered from the upper mantle by the host magma. It consists of forsterite, enstatite, chrome-diopside, and chrome-spinel. Sulfide and primary mantle carbonate are present as accessory minerals. A very rare locality!

Offered in polished slices.
Polished slices, in a 2'x2' plastic case, $38.00

.Corundum with Margarite and Hematite

.Corundum with Margarite and Hematite

This is hematite-laced corundum with veins of margarite! It was collected from the amphibolite facies emery deposits of Naxos, Greece, famed from antiquity. A very, very hard rock to cut and prepare from a locality steeped in history!

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

Ayer's Rock, Australia in thin section

.Ayer's Rock, Australia

.Ayer's Rock, Australia

Ayer's Rock is the largest, single, consolidated "rock" known in the world. It is dominantly composed of coarse-grained arkose, a type of sandstone characterized by an abundance of feldspar, and some conglomerate. Average composition is 50% feldspar, 25-35% quartz and up to 25% rock fragments that include subrounded basalts. Also known as "Uluru", Ayer's Rock is a sacred site for the Aborigine people. They maintain all rights over the site, forbidding climbing and sampling. These samples were acquired during the 1950's for research by an Australian prospector. Samples of Ayer's rock are almost impossible to obtain now.

Offered in polished slices.
Polished slices, in a 2'x2' plastic case, $38.00

Kimberlite, green hypabyssal rock, Central Montana, in thin section

.Kimberlite, Central Montana

.Kimberlite, Central Montana

This is Homestead Kimberlite from Central Montana. It's classified as a phlogopite-monitcellite-diopside-calcite-serpentine kimberlite. It's a great looking green mantle xenolith!

Offered in polished slices, micromounts
Polished slices, in a 2'x2' plastic case, $32.00

Eclogite Omphacite, Bravaria, Germany in thin section

Eclogite Omphacite, Bravaria, Germany

Eclogite Omphacite, Bravaria, Germany

Omphacite (the greenish matrix) is a major mineral component of eclogite (along with pyrope garnet). It also occurs in eclogite xenoliths from kimberlite as well as in crustal rocks metamorphosed at high pressures. Another great eclogite, this one is from the Münchberg Metamorphic complex, Franconia, Bavaria, Germany Bravaria, Germany.

Offered in polished slices.
Polished slices, in a 2'x2' plastic case, $32.00

Komatite basalt, Barberton Greenstone Belt in thin section

Komatite basalt, Barberton Greenstone Belt

Komatite basalt, Barberton Greenstone Belt

Named from their type locality along the Komati River in South Africa, komatiites are very rare. They're ultramafic volcanic rocks, having very low silica contents (~40-45%) and very high MgO contents (~18%). These lavas are exceptional not only for their compositions, but also for their very old, restricted ages. They have no modern analogs. From the Barberton Greenstone Belt in South Africa, komatiites are about three billion years old or older. These ancient lava flows erupted at a time when the Earth's internal heat was much greater than today, thus generating exceptionally hot, fluid lavas with calculated eruption temperatures in excess of 1,600 degrees C (2,900 degrees F). In comparison, typical basaltic lavas erupting today have eruption temperatures of about 1,100 degrees C.

Offered in polished slices.
Polished slices, in a 2'x2' plastic case, $32.00

Spitzbergen Basalt in thin section

Spitzbergen Basalt

Spitzbergen Basalt

Mantle xenoliths and their host basalts from the Spitsbergen archipelago (Norway) contain chemically zoned globules and patches of ankerite - magnesite carbonate minerals that are similar to the carbonate minerals of the very famous Martian meteorite ALH 84001. These carbonate globules may help shed light on the origin of the ALH 84001 carbonates. A difficulty in understanding the martian carbonate minerals has been the lack of comparable terrestrial occurrences for comparison. We now have, in the Spitzbergen basalts, a terrestrial analog that may help us understand the carbonate globules in this martian meteorite which is believed to contain evidence for relic biogenic activity from the martian surface.

Offered in polished slices.
Polished slices, in a 2'x2' plastic case, $38.00

Carbonatite, olivine-phlogopite-dolomite

Carbonatite, olivine-phlogopite-dolomite

This is a rarity: a Proterozoic carbonate deformed in the Mesozoic with its primary mineralogy completely preserved - phlogopite, fresh olivine. Also present in thin section, dolomite, apatite, zircon, and pyrochlore.

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

Bellshank Mine kimberlite in thin section.

Kimberlite, Bellshank Mine, texture.

Bellshank Mine Kimberlite

A very attractive kimberlite, locally referred to as "blue ground" from it's bluish-tinged matrix, kimberlites from the Bellshank Diamond mine are rarely available. Diamonds were originally found in weathered kimberlite which was colored yellow by limonite, and so was called yellow ground. Deeper workings encountered less altered rock, serpentinized kimberlite, which miners call blue ground. Lots of xenoliths in this one.

Offered in polished slices.
Polished slices, in a 2'x2' plastic case, $32.00

Lherzolite mantle rock in thin section

Lherzolite mantle rock

Lherzolite mantle rock

This is a beautiful garnet bearing Lherzolite mantle rock from more than 200 kilometers down, rich in chrome-diopside. It's a coarse grained, ultramafic, igneous rock that, excepting eclogites are probably the most attractive samples of the Earth's upper mantle that we have.

Offered in polished slices.
Polished slices, in a 2'x2' plastic case, $32.00

Kimberlite, Crater of Diamonds Mine, Arkansas in thin section

Kimberlite, Crater of Diamonds Mine, Arkansas

Kimberlite, Crater of Diamonds Mine, Arkansas

Crater of Diamonds, located southeast of Murfreesboro in Pike County, Arkansas, has a rich 100-year history of diamond mining. The kimberlite pipe is the eighth largest diamond-bearing deposit in the world and the average weight of Crater diamonds is about 0.2-carats. This kimberlite is greenish with abundant, small clasts and inclusions.

Offered in polished slices, micromounts
Polished slices, in a 2'x2' plastic case, $29.00

Dunite, Western Gneisses, Norway in thin section

Dunite, Western Gneisses, Norway

Dunite, Western Gneisses, Norway

Comprised of greater than 90% olivine, with minor pyroxenes and chromite, dunites are olivine-rich end-members of the peridotite group of mantle-derived rocks. They are coarse-grained, plutonic igneous rocks of ultramafic composition. Dunites from the Western Gneisses region are very old, brought to the surface thru ophiolite obduction

Offered in polished slices, micromounts
Polished slices, in a 2'x2' plastic case, $28.00

Carbonatite

Carbonatite, Oka, Quebec

The majority of carbonatites are Proterozoic or Phanerozoic in age. They are rare, peculiar igneous rocks formed by unusual processes and from unusual source rocks. The primary mineral content is highly variable, but it may include natrolite, sodalite, sovite, apatite, magnetite, barite, fluorite, ancylite group minerals, and other rare minerals not found in more "normal" igneous rocks. Recognition of these exotic rocks is also difficult, especially as their mineralogy and texture may not differ much from marble. This one, from Oka, Quebec is the most attractive carbonatite in our collection.

Offered in polished slices.
Polished slices, in a 2'x2' plastic case, $32.00

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Alkali olivine basalt, Lenderut, Kenya

Alkali olivine basalt, Lenderut, Kenya

Alkali basalts are relatively poor in silica and rich in sodium. They are silica-undersaturated and may contain feldspathoids, alkali feldspar and phlogopite and typically have mineral assemblages that lack orthopyroxene. Typically they're fine-grained, dark-colored, volcanic rocks characterized by phenocrysts of olivine, titanium-rich augite, plagioclase feldspar and iron oxide.

Offered in polished slices.
Polished slices, in a 2'x2' plastic case, $26.00

Carbonatite, olivine magnetite megacrysts in thin section

Carbonatite, olivine magnetite megacrysts