No reason for his resignation was given by AVZ, with the company thanking Eckhof "for his efforts over the past four years and (acknowledging) his significant contributions in securing the Manono lithium project".
For that work in securing AVZ's right to earn a 60% stake in Manono, Eckhof was issued 80 million shares early last year.
He retains 30.5 million of those shares, having raked in more than $8 million by selling stakes last September and earlier this month.
The latter divestments saw the stock drop around 30% and at circa A8c it remains at levels last seen in July last year as it began a run that saw it reach 37c in January.
Eckhof's exit from AVZ comes in a week when he also appears to have become persona non grata at new US-focused lithium junior Hawkstone Mining.
Meanwhile, AVZ has begun a scoping study at Manono that is expected to be completed in August, and attempted to shore up its market prospects in the face of its much reduced share price of recent times.
"We are in the strongest position in our lifespan," AVZ told the market.
"We are well funded with approximately $17 million in the bank, no debt and a strong pipeline of news flow over the next 6-9 months as we move Manono to a position where a final investment decision can be made to progress to production."
At a share price this week of 8.4c, AVZ was capitalised at $155 million.