TTR wants to suck up 50 million tonnes of the seabed each year in shallow water off Pātea to extract iron, titanium and vanadium.
The deal depends on TTR getting the necessary environmental consents and Manuka shareholder agreement.
The Environmental Protection Authority (EPA) initially granted consents to mine the seabed, and to discharge 45 million tonnes of unwanted sediment annually back into the marine environment.
Last October – following a seven-year legal fight by a dozen iwi, fisheries companies and environmental groups – the Supreme Court overturned those consents and sent the application back to the EPA.
The prospectors remain bullish: Manuka Resources told the Australian Stock Exchange it expects to win back the consents when the EPA reconsiders "five narrowly defined matters" early next year.
"TTR believes it meets the tests as laid down by the Supreme Court and does not anticipate further scope to challenge the re-grant of the consents."
But its path may not be so simple: the Supreme Court insisted the EPA must take a "broad and generous" view of its Treaty of Waitangi obligations, and take into account tikanga and kaitiakitanga.
Manuka's buyout statement did not specify how the renewed consent application would meet this standard.
Māori Party co-leader Debbie Ngarewa-Packer, of Ngāti Ruanui, said TTR was out of touch with how Taranaki now views seabed mining.
"They always underestimated iwi, they always underestimated the weight, the significance of our kaitiakitanga and mana whenua, the significance of the Tiriti – they always underestimated us.
"What's really great is there's a better understanding of indigenous rights and tangata whenua rights than when we started eight or nine years ago ... there's a different pressure."
The tumu whakarae (chairman) of Te Kāhui o Rauru, Mike Neho, said in October the Supreme Court victory showed iwi values could win legal fights.
"This is the first time that kaitiakitanga and tikanga have been tested at this level of law and this will be a game changer for recognition of iwi interests and decisions about the environment."
TTR said the sediment would settle harmlessly back on the seabed but opponents argued the waste plume and mining noise would harm marine mammals and other sea life.
The court told the EPA that if it was unable to impose conditions that prevent environment harm, the discharges must be prohibited and the application denied.
Ngarewa-Packer said seabed mining was "environmental vandalism and would wreak havoc on marine life and coastlines for decades to come".
Eggers said the deal with Manuka valued TTR at $50 million, or $200 a share – a mark-up from recent issuing at $125 – and Trans-Tasman shareholders would end up with about 37 per cent of Manuka Resources.
The deal would give the until-now private TTR mining scheme access to capital from Australia's much larger listed market: Manuka would need to raise some $US600 to set up mining.
Ngarewa-Packer said the overseas sale was typical of the mining industry in Taranaki.
"They've done exactly what we predicted five or six years ago – this is a normal trail that we see within the sector.
"When you're going to do that amount of desecration in our waters, in our oceans, we expect to have a lot more confidence about how long you're going to stay around.
"What we have is typical capitalist investors' language where they're on-selling it: they've made it look to the future shareholders – who probably don't know a hell of a lot about it – that it's all go."
Although Manuka Resources is a minnow in the enormous pond of Australian mineral extraction, the sums attached to mining the South Taranaki Bight are not small.
The stock exchange announcement figures it would cost US$93 million a year to run the ocean operation.
At today's prices that would give the company a profit of $560 million a year from iron ore and another $663 million for vanadium – not counting freight costs and onshore overheads. Healthy payouts from the bonanza would largely flow to shareholders across the Tasman.
Manuka expected to be one of New Zealand's largest exporters and employ up to 250 operational and 50 administrative staff, as well as indirectly creating a further 165 Taranaki jobs in support, engineering, logistics and port operations.
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