Mr. Eoin McGrath:

Sulphates are SO-24 ions that attach. That is gypsum. The transition from sulphides to sulphates is the major pyrite problem. A sulphide transitions to a sulphate, which changes the calcium carbonate into gypsum, leads to swelling and that is why we get the pyrite issue. If you are producing material to standard recommendation, SR 16, SR 18 or SR 21, it is incumbent on you to have a professional geologist look at your materials. They have to do what is called knowledge of the raw material, which is an assessment of the actual deposit. That means going to the quarry, assessing the quarry and identifying heterogeneities, perhaps, within the quarry. Sometimes we see a quarry where there is one lithology on one side of the quarry and another lithology on the other. One might be suitable for concrete production and the other not. That should be reflected in the geologist's report. The second part of that report is a petrographic assessment of the product, which is the actual aggregate, the crushed aggregate. That is your 40 mm, your 10 mm, your fines content or whatever is going to be put on the market for use in concrete for SR 16, as an example. That is where the role of the independent geologist comes in. To fulfil that role you must be essentially a chartered geologist and for SR 21 you must be on a specific register maintained by the Institute of Geologists of Ireland, which is the professional accreditation body. The register is available on its website.