Lithology

Wollastonite Skarn: A white to pale green, medium to coarse grained calc-silicate rock, forming units up to 30 meters thick, with a banded texture. The banding is the result of mineral segregations that range from millimetres to 10 of meters. The main constituents of the rock include Wollastonite (>35%), and diopside (typically >30%) with accessory feldspar (typically 5%-20%) and quartz (typically 2%-10%). The diopside is usually of the hedenbergite variety where zones are proximal to contact. The feldspar is predominantly a sodic end member plagioclase (albite) with minor microcline or oligoclase. Minor accessory minerals include calcite, garnet, graphite and sulfides (mainly pyrrhotite with minor pyrite, occasional trace galena and chalcopyrite). Trace minerals include: fluorite, idocrase, magnetite and sphene. Occasional alteration zones typically associated with north south fault structures contain talc and chlorite often totally replacing the calc-silicate mineral assemblages over widths locally exceeding 3 meters.

The contact between the Wollastonite skarn and the other metasedimentary units ranges from sharp to gradational.

The Wollastonite is translucent white, tabular to prismatic, medium to coarse grained (particle length, .2cm - 2cm). The average grade of the Wollastonite zones is 42%, with some sections reaching >80%. The texture is massive with no visible preferred orientation of the crystals except occasional flattening parallel to layering. The higher grade sections are typically coarser grained and friable. At outcrop scale the wollastonite bands are in low relief while the diopside skarn and quartzites are in high relief. This relationship is reversed in overburden covered areas where wollastonite bands are in high relief and diopside in low relief.

At map scale the wollastonite zones are associated with topographic highs, which may be a result of their resistance to glacial scouring versus the blocky silicate skarns.

Calc-silicate Skarn: Pale green, fine to medium grained calc-silicate rock with a banded texture. Based on a comparison of average mineralogies (>10% difference in average wollastonite content) it is probable that the calc-silicate skarn evolved from a separate unit (protolith) versus wollastonite skarn. It is rare however that there is a sharp break between wollastonite skarn and calc-silicate skarn, and more commonly a gradational contact is observed where the frequency and thickness of bands diminishes as one moves away from a particular band.

The calc-silicate skarn is defined as being >50% combined wollastonite and diopside with a wollastonite content between 20% and 35%. The calc-silicate skarn will frequently display a rusty surface weathering due to increased iron sulfide content.

Diopside Skarn: A pale green to green/grey rock with a rusty, weathered surface. Fine to medium grained, granoblastic, calc-silicate rock with a massive to banded texture. The width of bands ranges from centimetres to several meters. The clinopyroxene content ranges from 35% to 80% diopside. Major accessory minerals are wollastonite, quartz and feldspar. Minor to trace minerals are garnet, calcite, sulfides and graphite. The diopside grains are anhedral to euhedral and exhibit a varying shade of green throughout any one sample. The diopside skarn is more of the hedenbergite variety proximal to the intrusive contact where it exhibits the characteristic, darker green (iron rich) colour. Near the intrusive it occurs in conjunction with more frequent coarse-grained garnet and feldspar. Hedenbergite is also observed occasionally in narrow veins cross- cutting skarn zones, associated with coarse wollastonite and garnet in addition to diopside.

Silicate Skarn: Grey, fine to medium grained, anhedral quartz feldspar and diopside with minor wollastonite, garnet, sulfides and graphite. Combined quartz and feldspar content >50%. The silicate skarn is distinguished from the quartzite by its interbanded nature and accessory skarn mineralogy. The bands range from cm's to several meters. The surface outcrop exhibits a rusty weathering making it difficult to distinguish from diopside or calc-silicate skarn except in drill core.

Quartzites and Quartzofeldspathic rocks: White or grey, fine to medium grained, anhedral, massive, granoblastic, vitreous quartzite with varying amounts of white feldspar. They commonly exhibit a rusty appearance in outcrop due to their pyrite content. Enveloping the layered skarn sequence described above are thickly folded quartzite units up to 30 metres wide. Major accessory minerals in the quartzites include alkali -feldspars and plagioclase with minor diopside and pyrite and occasionally garnet and biotite. Minor, pink potassium feldspars locally form inter- layers.

Gneiss: Brown to grey, medium grained equigranular, foliated banded gneiss. Exhibits a rusty surface weathering. Constituents include phlogopite, plagioclase, quartz and sulfides where they occur within the skarn and also includes hornblende where observed in outer contact with the enveloping quartzite. This unit is found as meter thick to several meter thick bands bordering calc-silicate units in the central and northern portions of the property. Correlation of these bands suggest they are a good marker horizon.

Laminated Silica: White to pale blue, thinly banded to well laminated layers of massive quartz, averaging -2 meters in width. These bands are commonly located along the flanks of wollastonite skarns and can in some cases be used for correlation purposes. They are believed to be the result of silica flooding around the calc-silicate members.

Calcitic Marble: White, medium to coarse grained, massive to weakly foliated, granoblastic with a grey to black weathered surface. Bands of marble range from cm's wide within the quartzite fold to several meters outside. Accessory minerals include quartz, diopside and graphite. Locally, pyrite, feldspar, and wollastonite are observed. The weathered surface is highly friable and may exhibit high relief silica nodules or elongated silica knots. Chemical analysis of six marble samples in the vicinity revealed, relatively pure calcitic marbles with a slightly elevated SiO2 content in relation to the average for Grenville marbles. The amount of SiO2 and CaO or MgO can however vary considerably over areas less than 300 meters.

Pegmatitie: White to grey, coarse grained to pegmatitic, massive with a grey weathered surface. Feldspars make up >90% of this rock unit with minor amounts of diopside and quartz. These dyke like units are often located in the centre and flanks of wollastonite skarn units and may represent excess silica and carbon dioxide reaction zones. Regionally these white pegmatites are usually associated with marbles which supplied the carbon dioxide which has resulted in the reduction of ferric iron, turning these originally pink feldspars white. Major pegmatites are found north of the quartzite rim and to a lesser extent sub-parallel to the axial plane of the major fold.

Diabase: Black, fresh, fine grained, massive, narrow (5-20meter) dykes which cross-cut all Precambrian rocks in the area. They have a rusty weathering and are believed to occupy tension fractures along the apex of the Frontenac Arch. They are typically several meters in width and trend north-north west. The dykes are common (swarm) in the South Lake region. They are highly magnetic and contain amphibole, k- feldspar, mica, diopside, scapolite and sulfides. These dykes are typically associated with major north-south fault structures on the property.

Anorthosite Dyke: Fine to medium grained, white to grey, >90% plagioclase. Attain widths of 2 meters.

Gabbro: Grey to black, massive, phaneritic, granoblastic with a greyish-white to rusty weathered surface. No metamorphic overprint is observed. Colour index 40-70. The mineral assemblage consists predominantly of plagioclase, amphibole, pyroxene, biotite, minor quartz and sulfides including small veinlets of pyrite and chalcopyrite. This unit differs from other gabbros in the vicinity in that it contains an ophitic texture and little biotite. Although not observed in the field there is an apparent relationship between the gabbro and other intrusives in the area. The gabbro is reported to grade into syenite in the central and northeast section of the intrusive.

Syenite, Monzodirite and Monzonite: These intrusive rocks are commonly grouped under one heading on geologic maps of the area. The presence of these rocks, which are spatially associated with the gabbros appears to be a progression of phases from syenite through gabbro with the monzodioritic rocks proximal to the gabbro.