Base Metal Deposits

Deposit
Year of Discovery
Tonnage (Mt)
Grade (Zn + Pb)
Status
Navan
1970
105.1
10.20%
Operating Underground
Lisheen
1990
22.8
14.10%
Operating Underground
Galmoy
1986
9.7
16.20%
Closed Underground
Silvermines
1963
17.7
8.90%
Closed Underground
Tynagh
1961
9.2
11.20%
Closed Pit & Underground

Read about Irish Base Metal Exploration

Galmoy

The Galmoy zinc-lead deposit was discovered in 1986. Production commenced in early 1997 with total production to date being 9.7 Mt at 16.2% Zn+Pb.
Two separate sulphide orebodies occur approximately 70 m below surface and are hosted in basal Waulsortian (Lower Carboniferous) “Reef” mudbank limestones. The host rock has been extensively dolomitized and brecciated. The mineralization is regarded as being replacement/stratabound. There are four ore bodies with the G orebody being a classic “Irish type” deposit occurring in the hanging wall of a major northeast trending fault. 

Lisheen

ImageLisheen was discovered in 1990 and production commenced in September 1999. Total production to date has been 22.8 Mt at 14.1% Zn+Pb.
Mineralization occurs as massive stratiform sulphide lenses at the base of dolomitized Waulsortian (Lower Carboniferous) “Reef” micrites in the northern hanging wall of an ENE trending fault zone. 

Silvermines

In 1963, a drilling programme intersected ore-grade lead–zinc mineralization in Lower Carboniferous carbonates in the hanging wall of a northerly-downthrowing east trending fault zone. The mine produced some 17.7 Mt of ore grading 8.9% Zn+Pb until closure in 1982.
Mineralization is typically in the form of stratiform sedex massive sulphides occurring at the base of the Waulsortian “Reef” Limestone.
There is also an underlying epigenetic (veins, breccias) zone representing a feeder to the upper zone. The upper zone contained 12.94 Mt grading 6.78% Zn and 2.55% Pb, while the lower zone contained 4.74 Mt grading 5.49% Zn and 2.44% Pb.

Tynagh

This Lower Carboniferous carbonate-hosted, stratiform lead-zinc-copper-silver-barite orebody was found in 1961 as a result of conventional shallow soil geochemistry and geophysics (EM and IP). The mine commenced production in 1965 and the orebody was worked out by 1980. The deposit contained approximately 9.2 Mt grading 11.2% Pb+Zn.
The primary sulphide mineralization (galena, sphalerite and chalcopyrite) was hosted mainly as lenticular bodies in Waulsortian micrites in the hangingwall of an E trending fault. The higher grades of mineralization were found adjacent to the fault and towards the base of the Waulsortian “Reef” Limestone.

Navan

ImageThe Navan deposit, the largest zinc mine in Europe, the eighth largest in the world, was discovered in 1970. Total production to date has been 105.1 Mt grading 10.2% Zn+Pb.
This deposit is hosted in basal Carboniferous shallow-water carbonates and comprises a stacked series of massive stratiform and stratabound sulphide lenses aligned approximately NE and parallel with major faulting.

 

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