First, the good news. The Government's stocktake of the country's mineral wealth, released this week, finds that New Zealand is a "mineral rich country with considerable untapped potential".

It says few of us know that substances important to modern economies reside in our land, some critical to future technologies such as hybrid and electric cars, wind power and computer and communications equipment.

All up, we could be sitting, standing and gazing upon up to $194 billion in minerals, excluding hydrocarbons such as oil and gas.

But what does this really mean? The stocktake is the work of the Department of Conservation, which administers about 40 per cent of our land mass as public conservation land, and the Ministry of Economic Development.

Strange bureaucratic bedfellows they might be, but they represent the twin forces at work in the Key Government's "priority" of developing these mineral resources in an environmentally responsible way.

Where the inevitable tension arises is when the stocktake reveals that 40 per cent of that total mineral wealth is estimated to fall within the so-called Schedule 4 areas, restricted conservation lands that make up just 13 per cent of the country.

Awkwardly, the finest lands for conservation purposes are the richest in potential mineral wealth. Officials claim that as a potential positive, as the high concentrations would mean mining could be "very targeted".

Their report, as revealed by Forest and Bird before the Government could arrange its formal release, identifies areas in which they believe this can be achieved: on one plateau of Great Barrier Island, an area around Thames and two other parts of the Coromandel Peninsula and a zone in the Paparoa National Park in Westland.

Energy Minister Gerry Brownlee says these locations represent the relative size of a post card placed on the turf of Eden Park's main field. Conservationists are alarmed, one noting that news of these recommendations was as if the country had been asleep and had awoken again in the dark, mining days of the 1980s.

Both views are overstated.

Mr Brownlee's because it is not the size but the impact on value and utility of the land that matters. The anti-mining lobby ignores the fact that substantial advances in conservation of the past two decades are largely retained. The country's habitats will remain better off than before.

The Government is characteristically tentative in its proposals. Although introduced by Mr Brownlee and the Conservation Minister Kate Wilkinson, the document claims not to represent government policy.

The piecemeal removal of the areas from Schedule 4 protection, with an unconvincing attempt to include some other land and marine zones into its care as a sop to the green bloc, is unlikely to spark a gold rush any time soon.

There is a $4 million project to assess mineral potential on bigger swathes of protected land, with a hanging possibility of further zones being removed from Schedule 4.

Yet there is nothing in the stocktake about the possible economic upside, either in jobs or general benefits to GDP or direct financial gains for the Crown.

The amounts the Government might expect as royalties from private companies exploiting non hydrocarbon deposits are likely to be small. The absence of an economic case, even theoretical, is an important omission.

National is trying to make its case for elevating real economic advantages of mining over the intangible values of preserving flora and fauna, but it does not do so.

The report seeks submissions on its recommendations by early May, but how can one half of the equation be argued without the other?

So far, all we know is the potential downside, a reduction in the area of land given high protection. Without the economic benefits, that grand $194 billion figure is meaningless.