The Leo D'or marble prospect is located approximately 30 kilometres southwest of Port MacNeil on northern Vancouver Island. The property is situated at the northeast end of Bonanza Lake on a tree covered slope which rises from the lake shore to the east at an average slope of 30 degrees.
A band of limestone of the Upper Triassic Quatsino Formation, Vancouver Group, up to 2.5 kilometres wide, trends northward along the east side of Bonanza River and Bonanza Lake for 6.25 kilometres. To the west, the limestone is in fault contact with basaltic flows of the Upper Triassic Karmutsen Formation, Vancouver Group. An elongate stock of coarse-grained, biotite quartz monzonite of the Early to Middle Jurassic Island Plutonic Suite intrudes the limestone from the southeast. On the Leo D'or property, the limestone has been recrystallized to marble by these intrusions. Discontinuous dykes of basalt, averaging 60 centimetres in width, are also observed throughout the area.
Bedding in the marble has a regional dip of approximately 20 degrees; strike varies considerably. Locally, the beds are folded into tight synclines or anticlines, the limbs of which dip as steeply as 40 to 60 degrees. The fold axes vary in plunge from 0 to 65 degrees. A major fault trends north through Bonanza Lake and minor east trending faults cut through the property. The faults on the property have offsets up to 1 metre and are generally steeply dipping to both the north and south. Joints in the area are also steeply dipping and have variable strikes. Joint spacing varies from several centimetres to as much as 10 metres.
The marble varies in colour from very light grey to dark grey or almost black, to mottled grey and white. In some areas, distinct black to light grey bands of marble, varying from several centimetres to several metres, occur. The grain size of the marble varies from fine to coarse grained, the majority (approximately 75 per cent) is medium grained. Light brown to light orange surface staining is caused by the oxidation of iron impurities in the marble. The percentage of iron is estimated to vary from 0 to 4 per cent, locally. One bed on the property contains small cherty nodules and dips approximately 10 degrees to the east. Minor amounts of pyrite were noted in some of the thin (less than 5 centimetres) dark marble bands.
During a preliminary engineering study of the area in 1988, a preferred site, approximately 160 by 100 metres, was outlined for further evaluation based on its consistency of colour. The overall slope of the ground is 30 degrees, although individual faces are as steep as 45 degrees. The site consists of very light grey to white marble, with varying amounts of iron-staining on weathered surfaces. Very little colour banding was observed within this area. The majority of the rock is massive and for the most part hard and resistant to weathering. Some areas are blocky and dissected by joints.
A volume of marble available within the investigated area of consistent colour has been estimated, assuming that the rock is similar at depth to that on surface. It is further assumed that rock waste due to close joint spacing or karst would be 50 per cent, and that the quarry slopes would extend up at about 60 degrees. Based on these assumptions, a rock volume of 240,000 cubic metres (about 660,000 tonnes) would be available for quarrying (Industrial Minerals File - Broughton and Bruce, 1988). Petrographic analysis of the marble indicates that it consists of approximately 99.5 per cent grey to white calcite (Industrial Minerals File - Read, 1988).
In 1991, a short-hole drilling program consisting of 6 holes was undertaken to further assess the marble resource on the property (Assessment Report 22218). This time the area of examination was on "Onyx Hill" in the southeast part of the property, about 1 kilometre east-southeast of the above 1988 preferred area of investigation. Drilling encountered medium-grained, faintly banded, light to medium grey marble, the dominant rock type, which graded into creamy white to buff, medium-grained marble containing scattered 1 to 0.5 centimetre calcite crystals. The marble sequence is cut by a number of quartz porphyry and mafic sills, some up to 10 metres thick. The frequency of fracturing and jointing, as seen in drill cores, is reported to be within acceptable limits for extraction of blocks up to 15 tonnes. Two chemical analyses of selected core samples of marble indicated few impurities and CaCO3 contents of 99.14 and 99.51 per cent.
According to M. Shariatmadari (Personal Communication, 1992), in 1992, Leo D'Or Mining Inc. expanded the 1988 preferred site area to 250 by 180 metres by stripping and cleaning the surface. The marble in the expanded area proved to be of the same consistent quality as that described for the original smaller area. The total thickness of the marble based on one drill hole and various outcroppings is estimated to be at least 120 metres. Two 25-tonne white marble blocks were excavated from this area. In addition, 35 blocks were cut in 1993. Considerable potential exists to define a larger reserve of marble over the entire property based on distribution of marble outcrops over the entire property.
In 2015, White Rose Holdings Ltd. completed a minor program of geological mapping on the area. In 2018, White Rose Holdings Ltd. extracted two blocks of stone from the quarry for processing into samples for test marketing.
