The Rar 4 occurrence is located within the Rar 4 claim, in rugged terrain, 6.5 kilometres west of Mount Skook Davidson in the Kechika Ranges of the Cassiar Mountains approximately 153 kilometres east of the community of Dease Lake (Assessment Report 15220). This showing consists of fluorite and rare earth element mineralization associated with a mafic alkalic intrusive complex.

The geological region is characterized by a folded and thrust-faulted assemblage of siliciclastic and carbonate rock units ranging in age from Upper Proterozoic to Devonian and belonging to the Cassiar terrane (Fieldwork 1988; Geological Survey of Canada Maps 42-1962, 1712A, 1713A). The metamorphic grade is up to lower greenschist facies and is probably post-mineralization. The oldest rocks are the Ingenika Group, overlain by quartzite of the Lower Cambrian Atan Group. These are overlain by a thick succession of chlorite-sericite schists and phyllites, marble and dolostone correlative with the Cambro-Ordovician Kechika Group. Most of the Rar claims are underlain by Kechika Group phyllites, but within them is a northwest trending fault-bounded panel composed of grey limestone and dark green siliceous tuff, chert and sandstone in an isoclinal anticline cored by phyllitic limestone (Assessment Reports 15220, 16420, 20895, 22746; Fieldwork 1988). Based on fossils in the limestone, this tuff-chert-limestone unit is correlative with the Ordovician-Silurian Sandpile Group (Assessment Report 20895).

The mineralization is hosted by an alkalic, mafic syenite or malignite (melanocratic titan-augite syenite) dike or sill, which intrudes the siliceous tuff and chert unit in the upper southwestern limb of the overturned isoclinal anticline (Assessment Reports 15220, 16420, 20895). This intrusion is part of a west-northwest trending belt of alkaline igneous rocks, carbonatites and diatremes that has been mapped for at least 20 kilometres. The Rar 4 showing is toward the southeastern end of this belt; the most important deposit in the belt is the Kechika yttrium prospect (094L 017), 7.5 kilometres to the northwest.

At the Rar 4 occurrence, the dike complex is 50 to 150 metres thick and extends to the southeast into the Rar 6 claim for a strike length of approximately 3 kilometres. Locally, it strikes 148 degrees and dips 77 degrees southwest, slightly discordant with respect to the adjacent cherty tuff unit, in which the bedding strikes 132 degrees and dips 52 degrees southwest.

The mafic syenite dike is dark green, fine to medium-grained, moderately foliated and consists of hornblende or pyroxene, chlorite, alkali feldspar and biotite. The margins of the body are marked by brecciation and metasomatic alteration (Assessment Report 20895). The intrusion is strongly fractured and brecciated and filled with a stockwork of fluorite-calcite-biotite-epidote veins, stringers and cavity fillings, amounting to 8 to 10 per cent by volume. Some veins contain large biotite crystals up to 3 centimetres across. The stockwork veins contain significant values of rare earth elements, highlighted by 0.99 per cent lanthanum and 0.7 per cent cerium, obtained from grab sample Rar 1 (Assessment Report 15220). Associated phyllitic rocks may be radioactive and tuffs contain rare chrome spinel (Assessment Report 20229).

The upper margin of the dike, to the southwest, is composed of a coarse-grained leucocratic syenite phase, similarly veined with fluorite-calcite stockworks. Sparsely disseminated sulphides are also present in the intrusion.

A few hundred metres to the west of the mineralized dike, the cherty tuff unit is cut by several shear zones, up to 3 metres in width, which contain fluorite-bearing veins enriched in rare earth elements. Two samples with aggregate widths of 5 and 6 metres were analysed and found to contain rare earth elements with an average worth (in 1987) of $182 per tonne (Assessment Report 16420). Later work, however, de-emphasized the potential of these "fluorite shears" (Assessment Report 22746).

A diatreme breccia complex, including agglomerate, tuff and related sedimentary material, occurs in the centre of the intrusion. The diatreme contains rare chrome spinel xenocrysts and chrome mica.

Near the base of the sequence are trachytic or syenitic tuffs or flows, with mylonitic textures, containing phosphate-rich areas with yttrium mineralization. Much of the rocks in this complex are carbonate rich and may be described as carbonatites. A more detailed petrography of this complicated geology is given in Assessment Reports 18538 and 22746.

In April, 2001, Pacific Ridge Exploration Ltd. optioned the Xeno claims, which covered part of the showings, and followed with further staking.

In 2010, Paget Minerals Corp. acquired the property from Pembrook Mining Corp. and optioned it to Seymour Ventures Corp. In 2011, Rare Earth Industries Ltd. (previously Seymour Ventures Corp.) completed rock sampling on the property. Highlights include sample L649311, which assayed 0.1383 weight per cent total rare earth oxides plus yttrium (Assessment Report 32772).

See Rar 7 (094L 017) for further details.