2. 2
Overview
2
• Located in County
Westmeath, 90km west of
Dublin
• The Ballinalack deposit is
estimated to contain ~8 Mt
at 6.3% Zn and 1.0 % Pb
and is the largest un-
developed base metal
deposit in Ireland
3. 3
Discovery History
3
• The deposit was discovered
by Syngenore Exploration
Ltd. between 1965 and 1969
using shallow soils and
stream sediment
geochemistry
• Discovery hole drilled
in 1970
4. 4
Discovery History
4
• Approximately 130 holes
have been completed in and
around the Ballinalack
deposit
• Completed over multiple
campaigns by different
companies
• Relatively few >50 m drill
holes are outboard of
historic resource
5. 5
Regional Setting
5
• Located in a world class Zn-
Pb district
• Three operating mines (Navan,
Lisheen, Galmoy)
• Two historic operations
(Silvermines and Tynagh)
• New discoveries at Pallas
Green
• Located on a significant
regional gravity lineament
• The Tynagh-Ballinalack Trend
• Represents a major basement
controlling structure
6. 6
• Irish Zn-Pb deposits occur within Courceyan
limestones
• The main host rocks are the Waulsortian
Limestones named after their type area in
Waulsort, Belgium
• The other main host rock of Irish Zn-Pb
deposits are the Mixed Beds (Equivalent to
the Navan Beds)
Irish Zn-Pb Deposits
7. 7
Stratigraphy
• The Waulsortian is part of an overall
transgresssive sequence
• The Waulsortian limestones are massive
lime-mud build-ups that produce mounds or
knolls
• Thickness varies due to both onset of
mound building and development of
mounds and is related to fault activity
9. 9
Structure
• The Ballinalack Fault is a series of north-
east trending normal faults with offsets of up
to 150m and a surface extent of over 400m
• The Waulsortian is thickest on the hanging
wall side, indicating deposition and fault
activity were concurrent
• Most mineralisation occurs in the hanging
wall side.
10. 10
Mineralisation- Host Rock
• Mineralisation
occurs in both the
Birds eye micrite
unit of the Mixed
Beds(Navan Beds)
and the Waulsortian
reef.
11. 11
Mineralisation - Style
• Zn-Pb mineralisation
occurs as open space
filling sphalerite and
galena cements in
stromatactis cavities
and dolomitic solution
collapse breccias in
Waulsortian reef
limestones.
14. 14
Relogging
• In the summer of 2007 Teck undertook a
program of relogging of historic core
• It was discovered that the irregular
distribution of high grade ores within the
reef was dependant on sometimes relatively
small argillaceous bands and beds
15. 15
Argillaceous Beds
• These beds came in two
forms:
– crinoid rich floatstones
with frequent thin
argillaceous wisps
– Argillaceous lenses with
lower crinoidal content
• These “off-reef facies”
appear to act as aquitards
to fluid flow and have
concentrated minerals at
their boundaries.
