Virtual Museum ID: 19-BCGS-LWY1
The color in amethyst from most localities is unevenly distributed in the individual crystals. In amethyst geodes, it is often most intense in the growth zones under the rhombohedral faces (at the tips). Occasionally the color is deeper under either the r or z rhombohedral faces, giving the crystal a pinwheel appearance when viewed from the top. In prismatic crystals, the color may appear in phantom-like thin layers, while in scepters and skeleton quartz the color is often concentrated along the edges, and accompanied by smoky zones. Despite the intense color, the content of iron occupying Si positions in amethyst is rather low, in the 10-100 ppm range (Dennen and Puckett, 1972).
When heated to more than about 300-400°C, amethyst loses its violet color and often turns yellow, orange or brown, and then resembles the quartz variety citrine, but depending on the locality and the temperature during the heat treatment it may also turn colorless or - rarely - green (Rose and Lietz, 1954; Neumann and Schmetzer, 1984).
The information listed below relates to the current holding location or collection that the sample is from, and whether the item is viewable at that location or is part of a private collection. Coordinates are given as guides, and we remind you that collecting specimens from these locations is not allowed. Caution is advised visiting such sites and Below BC assumes no responsibility for any injuries or trespassing charges that may occur as a result of the viewer entering these sites.
Original Collection:British Columbia Geological Survey (BCGS)
Virtual Museum ID:19-BCGS-LWY1
Date Added to VM:2019-05-07
Sample Origin:Toodoggone area, B.C.
Specific Site:Lawyers Mine
Datum:09 (NAD 83)
Primary Mineral Formula:SiO2
Advanced Geological Information
The following section provides geological data relating to the specimen or the site it was collected from, when available. Information has been obtained from various sources including private and government datasets but may not be up to date. Any geological time periods or ages listed often relate to the primary geology of the area, and may not be the actual date of an event such as mineral formation.
Geological Formation:Toodoggone Formation (Hazelton Group)
Geological Period:Lower Jurassic
Stratigraphic Age:174.1 to 201.3 Ma
Minfile ID:094E 066
Lower Jurassic Toodoggone Formation (Hazelton Group) volcanic rocks form a northwest-trending belt at least 90 kilometres long and 35 kilometres wide preserved between the undivided Lower Jurassic Hazelton Group to the east and the Upper Cretaceous-Eocene (?) Sustut Group to the west. Where observed, they rest structurally on the Upper Triassic Takla (Stuhini) Group. Toodoggone pyroclastic and epiclastic volcanic rocks are a predominantly calcalkaline andesitic to dacitic subaerial succession. The region as a whole resembles a synclinorium in section from northwest to southeast. Potassium-argon studies of hornblende and biotite indicate the age of Toodoggone volcanism ranges from 204 to 182 Ma. This age appears to be divisible into two main groups: an older, lower stage of volcanism dominated by andesitic pyroclastics and flows characterized by widespread propylitic and zeolitic alteration; and a younger, upper stage of volcanism dominated by andesitic ash-flow tuffs which generally lack significant epithermal alteration. All the known epithermal gold-silver deposits and occurrences are restricted to the lower Toodoggone volcanics and underlying units (Fieldwork 1988).
Toodoggone volcanic rocks display broad open folds or homoclines with attitudes generally less than 25 degrees dipping predominantly to the west. The overlying Sustut Group sedimentary rocks are structurally unaffected and are horizontal. A northwest trending set of younger, steeply dipping faults and synvolcanic half-graben margins are the dominant structure in the region. Major structural breaks are postulated to have been caused, or be the result of, a northwest trending line of volcanic centres. Small stocks are also aligned northwest, suggesting they were also influenced by the same structural trend. Subsequent to volcanism and intrusion, young faults are recognizable as northwest-trending lineaments. Major north-northwest fault systems are from west to east: Attorney, Moosehorn-McClair and Saunders-Jock. Most prominent gossans are aligned along this configuration of faults. The Attorney fault system passes through the Lawyers property.
Two distinct mappable sequences of the Toodoggone volcanics, consisting of an older pyroclastic quartz andesite crystal tuff sequence (Adoogacho Member) and a younger trachyandesite sequence (Metsantan Member), are evident at the Lawyers mine property. The two sequences are intruded by mafic andesite dikes, and are overlain by pyroxene basalt. The volcanic sequence in stratigraphic order comprises: a) quartz andesite crystal tuff, b) fine grained to aphanitic chocolate brown tuff, c) welded trachyte tuff, and d) trachyte crystal and crystal lapilli tuff with interbedded volcanogenic greywacke. Structural relationships between the quartz andesite and the trachyandesite sequence suggest that the trachyandesite volcanism occurred along the faulted margins of a graben. Chalcedony and quartz breccias and stockwork veins with gold-silver mineralization occur along these graben margins.
The youngest rocks on the Lawyers property occur in the area of the Duke Ridge and Cliff Creek zones, and are volcanic flows. They consist of a megacrystic potassium feldspar ash-fall flow member and medium-grained andesite crystal and crystal lapilli tuffs with interbedded greywackes. At the Duke Ridge zone, a thin aphanitic brown tuff member is interbedded within the andesite crystal tuff.
Epithermal gold-silver mineralization at the Lawyers mine occurs in quartz vein stockwork bodies and chalcedony breccia zones which appear to be controlled by fracture systems related to graben margins. Three deposits have been discovered to date and are known as the AGB zone (Amethyst Gold Breccia zone), the Cliff Creek zone, and the Duke Ridge zone. The Cliff Creek zone, a parallel zone which lies approximately 1931 metres to the west of the AGB zone, extends for a strike length of at least 1609 metres. The Duke Ridge zone extends for at least 1219 metres, and is a cross structure between the Cliff Creek and AGB zones.
The volcanic pile of the AGB zone is cut by several north-northwest and west-striking faults related to the Attorney fault system. The major fault is the "D1" which strikes north-northwest and dips about 60 degrees to the west. The fault appears to be left-lateral with a major normal component. The Gopherite fault has a north strike, dips vertical, and is a splay of the D1. Several minor east-striking faults, subsidiary to the D1 fault, also occur in the area.
The AGB zone strikes north and extends for at least 548 metres with widths of up to 12 metres. Mineralization consists predominantly of native gold, native silver, electrum and acanthite with minor chalcopyrite, sphalerite and galena, in a gangue of chalcedony and quartz, and minor calcite. It occurs as fracture fillings in stockwork veins as well as in the matrix within breccia zones and is controlled by a north and north-northeast trending fracture system which dips steeply to the west. Potassium-argon dating of adularia from vein selvages yielded a mineralization age date of 180 +/- 6 Ma (Middle Jurassic) (Fieldwork 1985). Geometrically, the resulting veins and breccia zones crosscut the stratigraphy, emerge from the older footwall quartz andesites and pass through the younger overlying trachyandesite sequence. At lower levels within the quartz andesite, the AGB zone appears as a single distinct vein system, whereas in the upper levels, the system splays into two prominent zones. In cross-section, the whole system resembles a "Y" configuration.
Patterns of breccia observed in hand specimen and on a mine-wide scale indicate that the intensity of veining and associated fractures increases toward a breccia zone. In general, brecciation is more intense in quartz andesite, but the zones are narrow, with narrow alteration envelopes. The alteration envelopes consist of various clay minerals with limonite, goethite and hematite, and vary from 1 to 50 centimetres in width. Argillic alteration is more widespread in the overlying trachyandesite sequence than in the quartz andesite, and silicification is restricted to wallrock fragments within the chalcedony breccia zones and stockwork veins. In the aphanitic to fine-grained tuffs, the breccia zones are restricted to narrow hairline fractures whereas in the overlying welded tuffs and trachyte crystal tuffs, the breccia zones are thick and widespread and alteration (mainly argillic) is intense.
Within the breccia zones are at least four periods of chalcedony and quartz deposition. The colour of chalcedony varies from white to cream, green, grey to dark grey, red and opaque brown. Quartz, amethyst, and to a minor extent calcite, are present in the centres of veins and breccia zones, representing the last stages of open-space filling. Chalcedony breccias and stockwork veins are often rebrecciated in areas cut and offset by postmineral faults, such as the D1 fault. The matrix in the rebrecciated chalcedony breccias is predominantly limonite, various clay minerals, and to minor extent hematite.
Chalcedony breccia zones and veins in quartz andesite are bordered by bleaching and silicification of wallrock with quartz and chalcedony veinlets and hematite. Intensity of chalcedony veining and microbreccias increases with more extensive bleaching, silicification and argillization. Chalcedony matrix within breccia zones and veinlets is impregnated with hematite and various other iron oxide minerals, including minor jasper. A propylitic zone, consisting of chlorite, minor epidote and calcite veinlets, is peripheral to the zone of bleaching and silicification. Sericite is present only in minor amounts within the breccia zones and as narrow selvages.
Drillhole data and underground mapping suggest that the argillic zone is more developed at the higher levels and within the trachyte crystal and welded tuffs, with correspondingly smaller peripheral propylitic zones.
At the Duke Ridge and Cliff Creek zones, chalcedony breccia zones are similar to those in the AGB zone. However, the breccia zones are generally better defined with sharper vein boundaries and at least four periods of chalcedony and quartz deposition are present. Near the surface and near postmineral faults, the breccia zones are broken up, with wallrock fragments completely altered to clay. On Duke Ridge, the breccia zones appear to be refracted along the contact between andesite crystal tuffs and a fine grained tuff member. Breccia zones, as in the case of the AGB zone, do not form strong and well-defined zones in the fine-grained tuffs.
In the Cliff Creek and Duke Ridge zones, chalcedony breccia zones and stockwork veins are associated with pervasive argillic alteration. The alteration consists of various clay minerals with or without limonite, goethite, hematite, and manganese oxides and varies in thickness from about 5 to 50 metres. Propylitic alteration with chlorite, epidote, and to a minor extent calcite, is present peripheral to the argillic zone. Superimposed on these is a supergene alteration zone of various clays and limonite up to 30 metres deep. Gold and silver values are generally low within supergene altered areas.
The Cliff Creek zone contains indicated (probable) reserves of 422,591 tonnes grading 6.37 grams per tonne gold and 264.29 grams per tonne silver based on a cut-off grade of 3.42 grams per tonne gold. Inferred (possible) reserves are 103,205 tonnes grading 5.75 grams per tonne gold and 267.72 grams per tonne silver based on a cut-off grade of 3.42 grams per tonne gold (George Cross New Letter No. 171 (September 5), 1990). Indicated reserves at the Duke Ridge zone are 68,032 tonnes grading 7.3 grams per tonne gold (George Cross News Letter No. 95 (May 16), 1990).
A new vein zone was discovered within the area of intersection between the Cliff Creek and Duke Ridge structures. Trenching exposed a 200 metre strike length of strong veining with sampling yielding 4.79 grams per tonne gold and 145.34 grams per tonne silver across 1 metre (George Cross News Letter No. 171 (September 5), 1990).
Examination of polished and polished thin sections of chalcedony-quartz breccia samples from both the AGB and Duke Ridge zones reveal hypogene and supergene types of mineralization. In both types, the various ore minerals occur in microfractures, vugs, and grain and crystal boundaries of non-sulphide and non-metal vein constituents. The hypogene type is characterized by acanthite, native gold, electrum with minor sphalerite, galena, and chalcopyrite, with up to 5 per cent pyrite. In places, acanthite projects inward from the walls of vugs with calcite in the interstices. The main gangue vein minerals are banded chalcedony and quartz, and minor barite. Calcite and barite occur in centres of veins and as matrix in breccia.
The supergene type is made up of acanthite, native gold, and electrum with hematite, lepidocrocite, and goethite disseminated through the gangue constituents, and pseudomorphic after pyrite. Acanthite occurs in limonitic cavities or boxworks from which sphalerite, chalcopyrite and galena were probably leached out by acidic solution derived from the breakdown of pyrite.
At the AGB zone, silver to gold ratios show that silver values generally increase toward the north and at depth. The distribution of silver to gold ratios also indicates that the margins of the zone are richer in gold relative to silver.
The Lawyers mine operated in a pre-production phase during 1988; the mill was commissioned in December 1988. Commercial production began in March 1989, and all pre-production and production statistics for the operation were recorded in 1989.
The mine began production from the AGB zone where measured recoverable reserves as of December 31, 1989 were 384,338 tonnes grading 8.63 grams per tonne gold (George Cross News Letter No. 95 (May 16), 1990). This zone has been mined out and broken material processed.
Cheni Gold Mines Inc. has completed mining and milling the new and recently discovered Phoenix zone deposit during the fourth quarter of 1992. In total, 4852 tonnes were mined and milled at a calculated head grade of 46.2 grams per tonne gold and 2155.8 grams per tonne silver. The mill was modified to produce dore bars and a flotation concentrate. The cumulative recovery for gold and silver averaged 91.7 per cent and 89 per cent respectively. On December 16, 1992, the Lawyers mine was put on a care and maintenance basis for the winter months (George Cross News Letter No. 240 (December 14), 1992; George Cross News Letter No. 42 (March 2), 1993).
The Lawyers underground mine originally went into production in 1989 but the company downgraded reserves in 1990, significantly shortening the mine's life.
Production in 1991 includes ore from the Al deposit (094E 091, 099, 079).
In 1996, AGC Americas Gold Corp. acquired the Lawyers property. In 1997, AGC entered into a joint venture agreement with Antares Mining and Exploration Corporation. AGC acquired all the Toodoggone properties in July 1999. AGC is a subsidiary of Timebeat.com Enterprises Inc. Antares became Canesa Capital Corporation in September 1999.
Cheni Resources Inc. completed reclamation of the Lawyers mine in September 1998.
In 2003, Guardsmen Resources Ltd. completed a month-long program of prospecting, geochemical sampling and minor trenching in the former mine area. The program generated encouraging assay results, particularly in an area that may represent a southern extension to the mined AGB zone. A channel sample across the zone averaged 5.13 grams per tonne gold and 20.8 grams per tonne silver over 27 metres (Exploration n Mining in BC, 2003, page 22). Guardsmen vended the former Lawyers mine property to Bishop Resources Ltd. in 2003.
In 2004, Bishop Gold Inc. completed a large trenching program on the former property. Trenching exposed a vein system that is 300 to 400 metres northwest and along strike from the Silver Pond (South) prospect (094E 161) of similar description and is grouped with that MINFILE occurrence.
The following Inferred Resources was published by Bishop Gold Inc. in 2005 (Press Release, February 15, 2005).
During the period June 28 to July 4, 2006, Bishop Gold Inc. completed five NQ2 diamond drill holes totaling 647.7 metres in the southern and central parts of the Cliff Creek Zone on a converted legacy claim (tenure #510071) in the central part of the property. The 2006 drill area is shown on Figure 2. The drilling was carried out as a continuation to the northwest of a similar-sized drill program completed in October 2005, in which two zones of higher grade mineralization associated with intense silicification and fine grained sulphides were intersected. Hole 05-CC-03 returned 3.0 metres grading 12.34 grams per tonne gold and 71.9 grams per tonne silver and Hole 05-CC-05 returned 2.03 metres grading 6.69 grams per tonne gold and 37.93 grams per tonne silver. The latter hole bottomed in mineralization at 53.0 metres. It was terminated prematurely due to equipment problems and weather constraints.
The Lawyers 1-54 claims were acquired by Kennco Explorations, (Western) Limited. During 1970 a geochemical soil survey comprising 900 samples was carried out over 10 claims. Regional geological mapping and soil, silt, and rock geochemical surveys were carried out in 1971 over the property and nearby Kodah and Saunders claim groups. In 1972 further geochemical survey work was carried out over the Lawyers group and a magnetometer survey on the Kodah group. During 1972 a geochemical survey of approximately 130 soil and 50 rock samples, and trenching was carried out on the Lawyers group. Work in 1974 included a geochemical survey (220 samples), and 610.8 metres of diamond drilling in 4 holes on Lawyers 181 and 183.
In 1975, the ground was restaked as the New Lawyers 1-4 claims (48 units). Work during the year by Kennco included a geochemical survey (65 samples) over 0.5 line-kilometres on a 15 metre grid spacing, 713 samples over 6 line-kilometres at variable spacing, and 521 metres of diamond drilling in 6 holes on New Lawyers 1 and 4. One hole drilled in the Cliff Creek zone gave insignificant values.
Late in 1978 the property was optioned to Semco Mining Corporation, who in Fly 1979 assigned the option to S.E.R.E.M. Ltd.; the company name was changed to Serem Ltd. in January 1980. Adjacent claims were staked in the Law 1, Law 3, and Breeze groups (38 units). Exploration work during 1979 included trenching and diamond drilling; one hole was drilled on the Cliff Creek zone with disappointing results. In 1980 Serem assigned 50 per cent of its interest equally to Sudbury Contact Mines, Limited and Agnico-Eagle Mines Limited under a join t venture agreement (Serem joint venture). Work during the year included soil and silt geochemical surveys and trenching. Diamond drilling on the Amethyst Gold Breccia zone during 1978-81 totalled 7846.7 metres in 44 holes. In 1981 a crosscut adit at the 1750 metres elevation was driven to the breccia zone, and including a footwall drift and 4 crosscuts totalled 764 metres. At the end of 1981 Sudbury and Agnico-Eagle declined to participate in further work and their interest became subject to dilution to a minimum combined 20 per cent of net profits. The Kennco interest was diluted to 5%. Work in 1982-83 included trenching on the Cliff Creek zone and approximately 3597 metres of underground and surface diamond drilling on the AGB zone. Diamond drilling in 1983 totalled 3054 metres in 17 holes (eight on Cliff Creek, seven on Dukes Ridge, and two on AGE). Mineable reserves were calculated at 509528 tonnes grading 7.23 grams per tonne gold and 243.77 grams per tonne silver on the AGB zone, and probable drill-indicated reserves of 130,155 tonnes grading 7.44 grams per tonne gold and 294.86 on the other two zones (Northern Miner, Nay 3, 1984).
Serem Ltd, wholly owned by the French government, changed its name in September 1983 to Serem Inc. Work in 1984, including trenching and diamond drilling, resulted in expanding the reserve estimate. The 1984 drilling (7010 metres in 45 holes) included 19 holes in the Cliff Creek and 13 in the Duke Ridge zones and surface and underground drilling in the AGB zone. Work in 1985-86 was related mainly to feasibility and access studies. Work to the end of 1986 included 22298 metres of surface and underground diamond drilling, 7000 metres of surface trenching, 1303 metres of crosscuts and drifts and 179 metres of raising. Wright Engineers Limited in a March 1987 reported a further estimate of mineable reserves.
The company name (Serem Inc.) was changed in 1987 to Cheni Gold Mines Inc. With financial assistance from the Province the Omineca Resource Road was extended to the Sturdee Valley airstrip, 8.7 kilometres by road from the mine. Work on the property in 1987 included 10,432 m of diamond drilling in 49 holes on the Cliff zone and underground development for mining of the AGB zone. Reserves in all categories were estimated as 1,757,766 tonnes grading at 6.72 grams per tonne gold and 243.09 grams per tonne silver (George Cross News Letter, 18/11/87). Construction of a 500 tonne per day mill began early in 1988.
Mining was completed from 1989 to 1991 inclusive. A total of 19,869 tonnes was milled from which 5,401,981 grams of gold and 113,184,127 grams of silver were recovered. This included 60,000 tonnes mined from the Al (094E 091).
In 1992, Cheni terminates production on property after test mining at Cliff Creek and Phoenix Zones.
In 1997, Antares Mining and Americas Gold Corporation acquire property and do detailed airborne EM-Survey
In 2000 Guardsmen Resources stakes and acquires complete property.
Between 2000 and 2003 exploration by Guardsmen Resources occurred.
2003 Guardsmen options property to Bishop Gold; prospecting, geochemical sampling hand trenching was carried out. The program generated encouraging assay results, particularly in an area that may represent a southern extension to the mined AGB zone. In 2003, Guardsmen completed a month-long program of prospecting, geochemical sampling and minor trenching.
In 2004 Bishop Gold carries out backhoe trenching on M Grid. Bishop Gold Inc completed a large trenching program on the former Lawyers (MINFILE 094E 066) epithermal gold-silver property. The company focused its program on the plateau west of the Cliff Creek portal where prospecting in 2003 located high-grade gold-silver vein float. Trenching exposed four zones of epithermal quartz veining, brecciation and silicification, one to ten metres wide, over a northwest-trending strike length of about 400 metres.
In 2005 Bishop Gold drills 5 diamond drill holes on southern part of Cliff Creek zone. The 2005 drilling program consisted of 5 holes for a total of 860.35 meters in October 2005. Bishop Gold Inc. completed five NQ diamond drill holes totaling 845 metres to test both bulk and higher-grade vein potential in the southern part of the Cliff Creek zone. Four of five holes intersected 12 to 81 metre-wide zones of quartz breccia and stockwork veining which crosscut altered andesitic porphyry volcanic rocks.
Although the overall gold-silver grades of the wider stockwork zones were generally low, two holes did intercept narrower, higher-grade intervals of potential economic interest. The mineralization is open on strike to the north and has not been drill tested in the upper 200 to 250 meters from surface.
In 2006, Bishop Gold Inc. completed five NQ2 diamond drill holes totaling 647.7 metre in the southern and central parts of the Cliff Creek zone. All holes cut wide zones of quartz stockwork alteration grading, overall, less than 1.0 gram per tonne gold. Within the wider stockwork zone, all holes intersected one or more zones of intense silicification, brecciation and fine grained disseminated sulphides over core lengths from 1.1 to 5.6 metres.
In 2010, the Cliff Creek portal was re-opened to assess its integrity. In 2011, Guardsmen transferred ownership of the Lawyers project to affiliated company PPM Phoenix Precious Metals Corp. who attempted to fully dewater the flooded underground workings.
In 2015, PPM completed 26 diamond drill holes, totalling 4002 metres, on the Cliff Creek North and Duke’s Ridge zones. Drilling on the Cliff Creek North zone indicated that it has a minimum strike length of 225 metres and remains open along strike to the north west and to the south east. Drilling yielded intercepts including 7.74 and 5.98 grams per tonne gold with 355.1 and 246.3 grams per tonne silver over 4.86 and 4.10 metres in hole CC15-12, 9.64 grams per tonne gold and 307.0 grams per tonne silver in hole CC15-06, 1.71 grams per tonne gold and 74.5 grams per tonne silver over 51.99 metres in hole CC15-13 and 87.04 grams per tonne gold and 2407 grams per tonne silver, including 293.40 grams per tonne gold and 7622 grams per tonne silver over 0.70 metres in hole CC15-15 from a narrow semi-massive sulphide vein, referred to as the P2 vein, and associated stock work zone (Lane, R.A. (2018-04-30): NI 43-101 Technical Report and Resource Estimate on the Lawyers Gold-Silver Project). The P2 vein occurs approximately 70 metres into the hangingwall of the main Cliff Creek North zone.
Drilling on the Duke’s Ridge zone yielded intercepts including 8.54 and 3.85 grams per tonne gold with 171.8 and 106.5 grams per tonne silver over 4.00 and 8.56 metres, respectively, in hole DR15-04 an DR15-05 (Lane, R.A. (2018-04-30): NI 43-101 Technical Report and Resource Estimate on the Lawyers Gold-Silver Project). The two drill holes were located approximately 30 metres apart in the central portion of the mineralized zone which remains open at depth and has a minimum strike length of 380 metres.
In 2018, Crystal Exploration Inc. released updated mineral resource estimates for the Cliff Creek North and Duke’s Ridge zones, using a 4.00 grams per tonne gold equivalent cut-off, with an inferred resource of 550000 tonnes grading 4.51 grams per tonne gold and 209.15 grams per tonne silver for the Cliff Creek North zone and an inferred resource of 58000 tonnes grading 4.30 grams per tonne gold and 139.13 grams per tonne silver for the Duke’s Ridge zone (Lane, R.A. (2018-04-30): NI 43-101 Technical Report and Resource Estimate on the Lawyers Gold-Silver Project).