From the Severnoe Verkhnee multi-phase intrusive body. A fresh rock delivered from the upper mantle by the host magma. Mineralogy: olivine, orthopyroxene and subordinated chrome-spinel. Harzburgites are rarely seen in the East Antarctic volcanic rocks. Collected during the Australian summer of 1986 near the western edge of the Lambert Glacier, East Antarctica.

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

Eclogites are some of the most dramatic appearing rocks to be transported from the upper mantle. The Borborema Province, in the NE of Brazil, is a rather complex piece in the Brazil-Africa puzzle and a world-class locality of extraordinary geologic diversity. Eclogites consist primarily of green pyroxene (omphacite) and red garnet (pyrope), with small amounts of various other stable minerals i.e., rutile.

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

Olivine Melilite in thin section

Olivine Melilite groundmass

Olivine Melilite slice

This is a very fresh, rare, intrusive rock with glassy phenocrysts of olivine. Samples also contain phenocrysts of melilite, and clinopyroxene with groundmass perovskite and thin zeolitic veins. Research indicates that these melilitites are near-primary magmas, probably derived as small-degree partial melts from the base of the lithosphere, which had previously been enriched over time by melts ascending from the asthenosphere below. Melt production in the asthenosphere is believed to have begun at 100-200 km depth beneath the Rhinegraben, within the dolomite-phlogopite-garnet stability field.

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

Thin section unavailable.

Dunite with Wehrlite veins.

Dunite with Wehrlite veins.

This is coarse dunite (peridotite) with even coarser clinopyroxenite (wehrlite) veins. It's a completely undeformed intrusive rock emplaced within upper mantle residual harzburgite. In summary, a coarse dunite (peridotite) was intruded by multiple generations of wehrlite (clinopyroxenite). In the polished surface there are visible small black grains of chromite.

Offered in polished slices.
Polished slice, in a 2"x2" plastic case, $33.00

Benmoreite in thin section

Benmoreite surface

Benmoreite prepared section

Benmoreites are extrusive, transistional, members of the alkali basalt magma series. With increasing magmatic differentiation, by inceasing SiO2 content, the series is alkali-salt-hawaiite-mugearite-benmoreite-trachyte. The type locality after which the rock is named is Ben More on the Isle of Mull, Scotland.

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

Kenyte thin section not available

Kenyte (anorthoclase phonolite)

Kenyte (anorthoclase phonolite)

This specimen was collected near Meteorological Station, Mount Kenya, Kenya. It is a coarsely porphyritic anorthoclase phonolite. It is dominated by large phenocrysts of anorthoclase, smaller phenocrysts of nepheline, and minor but prominent fayalite crystals. Mount Kenya is the type locality

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

Dickson County Kimberlite in thin section

Dickson County Kimberlite

Dickson County Kimberlite prepared slice

To date, more than 20 distinct kimberlites have been discovered in Michigan. These post-Ordovician intrusions range between 20 acres on average and follow a crude northwest trend through Iron, Dickinson and Menominee Counties. Data obtained from several kimberlites place them between approximately 186 and 209 ma. While none of the bodies discovered so far have been proven to be economic, it is believed that many undiscovered kimberlites exist in the Great Lakes region. Some of these bodies may be the source of the large historical diamonds found in glacial and alluvial sediments throughout the midwestern United States. These samples of kimberlite were found in Hylas, a historic locale, located about three miles east of Hardwood, in Diskson County, Michigan. It was a station on the Chicago and North Western Railway Railway, named by the railroad for Hylas from Greek mythology. The samples are well-rounded similar to river stones and there are no known kimberlite pipes in the area so an association or locality is unknown.

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

Ugandite thin section not available at this time

Ugandite

Ugandite

Indaia consists of two intrusive plugs, appropriately named Indaia I and II. This is a very fresh ugandite from Indaia II. It's a sparsely olivine-phyric, fine-grained hypabyssal rock; the olivine is glassy and entirely fresh. The groundmass is predominatly diopsidic clinopyroxene with phlogopite, spinel, perovskite, nepheline, and glass!

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

Mafic Syenite in thin section

Surface texture

Mafic Syenite prepared slice

Specimen 15-27, described on catalog page 1, is from the same locality as this syenite but it's from the other magmatic series. This specimen is a very fresh, medium-grained rock from the syenite series dominated by nepheline, augite, and amphibole (kaersutite/barkevikite) with magnetite, apatite, titanite as well as minor alkali feldspar and sodalite. The nepheline and feldspar are undeformed within a foliated mat of augite and amphibole probably resulting from compaction near the solidus.

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

Fazanda Alagoinha kimberlite in thin section

Fazanda Alagoinha kimberlite

Fazanda Alagoinha kimberlite section

Kimberlites, the host rock for diamonds, found in the Fazanda Alagoinha region of Minas Gerais, Brazil, are transistional between the group I and II kimberlites of South Africa. But little is known about the kimberlite intrusions in the area because all the discoveries were done by foreign companies operating in the country. The groundmass of this specimen is studded with pyrope garnet.

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

Olivine Lamproite pyroclastic flow in thin section

Olivine Lamproite

Olivine Lamproite

Diamonds occur as sparse xenocrysts and in mantle xenoliths within olivine lamproite pyroclastic rocks and dikes. Many deposits are found within funnel-shaped volcanic vents or craters. Specifically, lamproites are ultrapotassic mafic rocks characterized by the presence of olivine, leucite, richterite, diopside or sanidine. This sample is from the Argyle lamproite vent in West Australia, Australia.

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

Olivine Melilite hypabassal rock in thin section.

Olivine Melilite hypabassal rock

Olivine Melilite

From the intrusive core of the Howenegg Volcano, this specimen is very fresh, with glassy phenocrysts of olivine. The mineralogy includes clinopyroxene, melilite, nepheline, magnetite, also traces of perovskite, biotite, and spinel.

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

Alnoite, Hicks Dome in thin section

Alnoite, Hicks Dome

Alnoite, Hicks Dome

The oldest rocks of the Herod quadrangle, in Pope, Hardin, Saline, and Gallatin County, Illinois, USA, are Devonian at the apex of Hicks Dome, an uplift that resulted from Permian igneous activity and is related to a crypto-volcanic event that produced pipe-shaped diatremes. Radiometric dating indicates early Permian of about 270 Ma. years ago. Alnoite carbonatite rock consists of melilite, biotite, pyroxene, calcite, and olivine. Feldspar is not present in the rock, its place being taken by the mineral melilite. The type location for this rock is Alnö island off the coast of Sweden.

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

Eclogite, Syros, Cycladic Islands in thin section

Eclogite, Syros, Cycladic Islands

Eclogite, Syros, Cycladic Islands

All eclogites from Syros are very attractive rock assemblages. They are almost exclusively limited in distribution to mafic complexes near the middle of the island. Samples are typically coarse-grained, massive, omphacite-rich rocks with assemblages that vary from omphacite-garnet-epidote-phengite to omphacite-garnet-epidote-glaucophane, with minimal amounts of rutile, titanite and quartz. Chlorite occurs as a common retrograde mineral and apatite occurs as an accessory mineral.

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

Harzburgite, Hokkaido Island in thin section

Harzburgite, Hokkaido Island

Harzburgite, Hokkaido Island

This is a rare specimen from the Horoman peridotite body, Samani-cho, Samani-gun, Hidaka Province, Hokkaido Island, Japan. It's a sample of a complex, layered, peridotite body with a harzburgite/Iherzolite emplacement related to oceanic mantle, subsided to deeper mantle depth, before crustal ascension and emplacement (23 Ma).

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

Eclogite, Robert Victor Diamond Mine thin section

Surface texture, Eclogite, Robert Victor Diamond Mine.

Prepared slice, Eclogite, Robert Victor Diamond Mine.

Roberts Victor Mine, Boshof, Free State Province, South Africa. Located about 40 km east of Boshof it's a diamond mine in a kimberlite deposit consisting of two dykes, one of which is associated with two pipes. The diamond grades and qualities of the different kimberlite bodies varied considerably. In general, diamonds from the pipes were of poorer quality than those from the dykes. Some parts of the latter contained diamonds of exceptional quality. This is eclogite from one of the dykes.

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

Boar's Tusk Kimberlite in thin section

Boar's Tusk Kimberlite.

Boar's Tusk Kimberlite.

Boars Tusk forms a prominent volcanic neck of wyomingite (phlogopite-leucite-lamproite) rising 300 feet above the valley floor. The neck is an agglomerate with abundant xenoliths and breccia fragments of lamproite. This kimberlite was found at the base.

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

Olivine Melilite hypabyssal rock, Mahlberg Castle in thin section

Olivine Melilite hypabyssal rock, Mahlberg Castle

Olivine Melilite hypabyssal rock, Mahlberg Castle

The Mahlberg castle is built on top of a volcanic neck composed of this melilite. The only outcrop is in the basement of the castle. Olivine melilites are extremely rare rocks. This one is exceptionally fresh and very dense with glassy phenocrysts of olivine. Also contains phenocrysts of melilite and clinopyroxene with groundmass perovskite.

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

Wollastonite urtite in thin section

Wollastonite urtite