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GEOLOGY AND ORE DEPOSITS OF THE SAN DIMAS
SILVER-GOLD DISTRICT, SINALOA AND
DURANGO, MEXICO
March, 2003
CULIACAN CITY
NORTH
DURANGO STATE
SINALOA STATE
San Miguel de Cruces
THE SAN DIMAS
DISTRICT
Tayoltita
San Ignacio
DURANGO CITY
Coyotitán
El Salto
Tucson
0
El Paso
200
MAZATLAN
KILOMETERS
Hermosillo
SIERRA
MADRE
OCCIDENTAL
TMVP
500
0
KMS
México City
LOCATION MAP
SAN DIMAS COMMUNICATIONS
125 kilometers northeast of Mazatlán
150 kilometers west of Durango
247 kilometers to Durango by road
TRANSPORTATION:
Twin Otter, 18 passengers
Helicopter , 4 passengers
PRDUCTION FROM SOME WORLD CLASS
EPITHERMAL Au-Ag DEPOSITS
DEPOSIT
TONNES oz. Au
oz. Ag oz. Au Equiv.
PACHUCA1
100
7.0
1,500
30.1
GUANAJUATO2
70
4.0
1,000
19.4
SAN DIMAS 3
19
9.1
654
19.2
COMSTOCK4
19
8.3
192
11.3
TONOPAH 4
9
1.8
174
4.5
4.5
2.1
1.5
2.1
OATMAN4
DATA GIVEN IN MILLIONS
Data from 1Drier, 1976; McKee, 1992; 2Gross, 1974; 3Henshaw, 1953;
3Smith and Hall, 1974; 3Enriquez, 1985, 1996; 4Buchanan, 1981.
BRIEF HISTORY
1757
Spaniards established first mining operations
1883
Modern mining methods were started in the district
1911
The Mexican Candelaria Mining, Co. is incorporated
1959
Mexicanization of the mining industry in Mexico
1967
San Luis Mining Co. was listed on the stock exchange
1979
San Luis Mining Co. was acquired by Luismin
1987
The San Antonio Mine starts operations
1991
The Santa Rita Mine starts operations
2002
Minas Luismin was acquired by Wheaton River Minerals
TUCSON
TUCSON
UNITED STATES
EL MALACATE
DOLORES
MULATOS
LA COLORADA
SIERRA MADRE
SILVER-GOLD
DISTRICTS
EL SAUZAL
METATES
GPE. LOS REYES
SAN DIMAS
DISTRICT
MAZATLAN
LA CIENEGA
BACIS
DURANGO
MEXICO
BOLAÑOS
GUANAJUATO
N
Pacific Ocean
PACHUCA
MEXICO CITY
0
300
KILOMETERS
MAJOR GOLD AND
SILVER DISTRICTS
ALONG THE SIERRA
MADRE
105°56’
EXPLANATION
UPPER VOLCANIC GROUP
O
NG
RA
DU
OA
AL
SIN
CARBONERAS
PIAXTLA INTRUSION
ARANA DIORITE AND
INTRUSIVE ANDESITE
HIL
UC
AM
GU
25°
NORTH
LOWER VOLCANIC GROUP
ARANA
33°
35°
FAULT
VEIN
O
FIRI
POR
DON
35°
10°
GEOLOGIC BOUNDARY
35°
35°
TAYOLTITA
ITO
ONC
LIM
T
FAUL
PEÑA
76°
CONTRA
ESTACA
35°
STRIKE AND DIP
TOWNSITE
24°6'
MILL
0
1
2
3
4
5 Km
34°
(After Henshaw, 1953; Randalll,1970; Smith and Hall, 1974; Nemeth,1976;
Clarke, 1982; Enriquez,1995).
GEOLOGY OF THE SAN DIMAS DISTRICT
F orm a tion Me m be r
U p p e r V olca nic G roup
T e r t ia r y
Age
C a pping
Thickness
(m)
STRATIGRAPHIC COLUMN
OF THE SAN DIMAS DISTRICT
>1500
R hyolite
G ua risa m e y
Andesite
Las P a lma s
200-300
Unconformity
Intrusive
Andesite
30-300
L ow e r V olc a nic G roup
U p p e r C re a tc e o u s
Fo ra mtion
C a michin
Productive
Porta l R hyolite
50-300
300-850
50-250
Buelna
20-75
S ocavon
250-750
R hyolite
Diorite
?
Bola ños
D ike
Veins
veins
Pia xtla
Intrusive
Sa nta R ita D ike
S a n Luis Dike
CEDRAL
SAN DIMAS
CANDELARIA
NTE
ICE
V
SAN
BLENDITA
CORONADO
IA
CEL
O
OR
L
E
S. RITA
TUNNEL
EL SOL
TAYOLTITA
MILL & TOWN
1,300 TPD
SANLUIS TUNNEL
ESCONDIDO
TUNNEL
LA
TA
ER
PU
PIAXTLA RIVER
5 HERMANOS
ÑA
PE
S.
LT
AU
OF
CIT
ON
LIM
ULT
O FA
FIRI
POR
DON
GUADALUPE
IS
UD
A
TR
R
CÍ
GE
LU
PATRICIA
S.
NI
ÑO
S.ANTONIO
TAYOLTITA
TUNNEL
T
UL
FA
HIL
UC
AM
GU
SA
ERE
S. T
GUARISAMEY
CLAUDIA
ITA
ERT
B
O
R
SAN ANTONIO
MILL 400 TPD
SR
ES
.
S. FERNANDO
TUNNEL
EL
FA
A
R
S.
S. EDUARDO
ALEX TUNNEL
CI
NC
O
A
ANZ
R
E
ESP
CULEBRA
SA
NL
UIS
SAN VICENTE
NA
BUE
E
H
NOC
ARANA
Z
LU
ES
EY
R
Y
MINITAS
EL CRISTO
AREA
IEL
AN
D
.
S
EL RELIZ
N
HÍ
IC
M
CA
0
1
Tunnel
Vein
Fault
River/
Creek
Town
Mill
2 km
VERDOSA
STRUCTURAL MAP OF THE SAN DIMAS DISTRICT
Geothermal System
SAN DIMAS
Volcanic - Hydrothermal System
100°
C O2 , H2 S
500°-900°
SO,2 HCl, CO 2
Crater lake
200°-300°
CO,2 HCl, S
M
et
eo
ric
200°
sulf
id at
ion
ing
Bo il
A u-
Ag
Saline magmatic fluid
Liquid flow
Vapor ascent
w
300°
High Sulfidation
Au, Cu
P
n eu r imar
tra
y
l iz a
tio n
DESCRIPTION OF
THE DEPOSIT
6 00°
Lo w
300
°
Hotsprings
Porphyry
Cu (Mo, Au)
at
er
From Hedenquist, 1996
q
q
q
q
q
1 km
Approximate scale
Epithermal veins of Bonanza style, Tertiary in age
Host rocks mainly andesites and rhyolites
Low Sulfidation type (Ag-Au)
Low Temperature (220-260 °C)
Simple mineralogy (pyriate-galena-sphalerite-silver sulphides
electrum-free gold)
q Pervasive propilitic alteration of host rocks
q Geochemical signature of As and Sb at top of the systems
q Low tonnage-High grade
S
EARLY
T A
G
E
S
ORE SUBSTAGES
QTZ--CHL
QTZ
CHL--AD
QTZ-RHOD QTZ
QTZQTZ--CAL
QUARTZ
CHLORITE
ADULARIA
RHODONITE
RHODOCHROSITE
CALCITE
SULFIDES
MAGNETITE
HEMATITE
GENERAL PARAGENESIS
LATE
SULF
BX
RHOD+SULF
1.0 METER
QUARTZ-RHODONITE SUB-STAGE
CHLORITE-ADULARIA ORE SUB-STAGE
QTZ-RHODONITE SUB-STAGE CROSSCUT
BY THE LATE QTZ STAGE
MINERALOGY
ORE
•
•
•
•
•
•
•
GANGUE
Acanthite
Argentite
Jalpaite
Stromeyerite
Pearceite-Polybasite
Electrum
Free gold
•
•
•
•
•
•
Quartz
Calcite
Rhodonite
Adularia
Rhodochrosite
Chlorite
OTHER SULFIDES (< 1%)
Pyrite-Sphalerite-Galena-Chalcopyrite-Chalcocite
VEIN RELATED ALTERATION
WALL ROCK ALTERATION
QUARTZ
CHLORITE
SERICITE
ALBITE
VEIN
ADULARIA
CALCITE
EPIDOTE
PYRITE
HEMATITE
MAGNETITE
ALTERATION SUMMARY OF THE SAN DIMAS DISTRICT
ELEV.
0m
TRACE ELEMENT ZONATION
SURFACE
ARGILLIC
ALTERATION
As
Sb
250 m
500 m
STOCKWORK
BONANZA
ORE SHOOTS
Au
Ag-Au
Pb
LOWER ZONE
NO ORE
1000m
Zn
Cu
GEOCHEMICAL MODEL OF THE SAN DIMAS DISTRICT
SE
SE
PATRICIA VEIN
NW
NW
W
E
Ore Shoots
ite
Andes
Buelna Andesite
ite
Rhyol
Socavon Rhyolite
Granite
EXPLANATION
PRODUCTIVE ANDESITE
PORTAL RHYOLITE
FAULT
ORE SHOOT
0
1 km
BUELNA ANDESITE
SOCAVON RHYOLITE
PIAXTLA GRANITE
LONGITUDINAL SECTION OF THE GUADALUPE VEIN
W
E
Guadalupe Vein
0
3 Km
SECTIONS ACROSS THE SAN DIMAS DISTRICT
SURFACE
Ag/Au INCREASE
LOW Ag/Au
Ag/Au INCREASE
HIGH GRADE ORE BODIES
X
X
30% of the Favorable
Zone is economic ore
X
X
X
EXPLANATION
X
X
X
X
INTRUSIVE
BODY
X
X
Quartz
Favorable
Zone
Ore Shoot
0
1000
2000
Meters
After Clarke, 1982
GEOLOGIC EXPLORATION MODEL FOR
THE SAN DIMAS DISTRICT
HISTORICALLY 88% CONVERSION RATE OF
RESOURCES TO RESERVES
Mine
Percentage
Tayoltita Mine
89
Santa Rita Mine
93
San Antonio Mine
Information based on a research carried out from 1979 to 1998.
73
San Dimas
Average
88%
RESERVES AND RESOURCES
As of December 2002
CATEGORY
PROVEN
PROBABLE
TOTAL
INFERRED RESOURCES
ORE
GRADE (g/MT)
M-tonnes
1.016
1.344
2.360
Ag
357
391
376
Au
3.90
4.54
4.26
12.5
308
3.01
*Gold Equiv. based on US$325 gold, Us$4.50 silver
CONTENTS (M oz) M-OUNCES
Au equiv.
Ag
Au
12
0.127
0.291
17
0.196
0.434
29
0.323
0.725
124
1.209
2.949
SAN DIMAS
DISCOVERIES FROM 1975 TO 2002
Development of the
El Cristo, Arana HW, Guarisamey
Central Block and San Vicente
vein systems
Reserves
Au Eq. oz. (000)
Cedral vein
system was
discovered
1400
1200
San Luis orebody mined out
San Antonio mine
starts production
San Antonio vein
system was
discovered
1000
800
Completion of the San Luis Tunnel
Start development of the Central
Block vein system: Celia,
Robertita, S. Lucia veins.
Patricias veins
were discovered
Santa Rita mine
starts production
Completion of
Tayoltita Tunnel
4.5 km.
Production
Au Eq. oz. (000)
250
Ma Elena, Elisa and Aurora
vein system was
discovered
200
Magdalena vein
system was
discovered
150
600
100
400
50
200
0
0
1975
1980
1985
Reserves
1990
Production
1995
2000
Predicted Reserves
2005
SCHEMATIC FLOW SHEET
SAN DIMAS DISTRICT
UNDERGROUND
MINE
DORE
BARS
CRUSHING AREA
PRECIPITATION
AND SMELTER
MILLING SECTION
CHEMICAL
TREATMENT
TAILINGS
DAM
PROCESS OF PRODUCTION
TAYOLTITA MILL
CHEMICAL TREATMENT
CYANIDATION AND MERRILL CROWE PRECIPITATION
FINAL PRODUCT: DORE BAR (32 kg)
COMPOSITION
Ag
95%
Au
0.8 – 1.0 %
Fe, Zn, Pb, Cu
< 4%
MILL CAPACITY
1,300 TONNES/DAY
OPERATING RESULTS
SAN DIMAS, 2002
CONCEPT
Mine Development
km
17.93
Milling
Au Grade
Ag Grade
Au Recovery
Ag Recovery
kton
g/t
g/t
%
%
453
4.5
371
97.3
93.8
Au Produced
Ag Produced koz
Au Eq
koz
koz
koz
64
5,057
139
Mine Operating Costs
Capital Costs
kU$
kU$
22,958
2,971
U$/Au Eq oz
U$/Au Eq oz
U$/Au Eq oz
165
11
176
Direct mining expenses
Realization Cost
Cash Costs
SAN DIMAS DISTRICT