Thank you for joining today's teleconference for the release of Mount Gibson Iron's March quarter activities report. Mount Gibson Chief Executive Officer, Peter Kerr, will be leading the discussion and is joined by Chief Financial Officer, Gill Dobson, and External Relations Manager, John Phaceas. Peter Kerr will provide a brief overview, after which there will be an opportunity to ask questions. Due to time constraints, only institutional participants will be invited to ask questions at that time. A recording of the call will also be available via the Mount Gibson website shortly after completion of today's teleconference. Please go ahead, Peter. Thank you.
Thanks, Bethany. Good morning, all. Thanks for joining us to discuss Mount Gibson's March quarter report. As usual, I'll give a brief overview before handing back to Bethany at the end for any questions you may have. Activity in the March quarter focused on the overburden stripping program investment at Koolan Island and the development of the Shine iron ore mine in the Mid West . At Koolan Island, despite the record wet season rains, we progressed the overburden stripping program in the main pit reasonably well. That remains on track for substantial completion during the second half of this calendar year. This program is key for our business, as people know, as it will set up the mine for reduced costs and significantly increased sales and cash flows for the remainder of its life.
We also finalized the ground support plan for the main pit's upper western end footwall and commenced the crushing plant upgrade. At Shine, we made very good progress and we're on track to commence initial shipments early in the September quarter. In terms of overall iron ore sales, we shipped just over 230,000 tonnes from Koolan Island, with one additional late quarter shipment actually deferred to April, due to a shipping delay. Group sales for the nine-month period to the end of the quarter total 2.5 million tonnes, and that includes sales from Koolan of 1.3 million tonnes. This is consistent with our guidance for Koolan Island for this financial year of around 1.8 million tonnes, and for group sales of between 2.8 million and 3.3 million tonnes.
Sales revenue totaled AUD 30 million FOB, and we report everything FOB. Reflective of the lower sales volumes and grade specifications as the overburden stripping investment is undertaken at Koolan. Also, remembering that sales from the Mid West operation from our Extension Hill mine site were successfully completed back in late December. Our sales revenue for the nine-month year- to- date totals 269 million FOB. Reflecting the Koolan Island stripping phase and inventory build, the group's unit cash costs, so that picks up everything other than the capitalized stripping and capital project investments, averaged AUD 135 FOB per ton sold, obviously reflecting that lower sales volume. Cash and investment reserves reduced by 24 million over the quarter and were AUD 412 million at March 31. The company has no borrowings.
This cash change reflected a net investment of AUD 34 million at Koolan Island, Shine development costs of AUD 11 million, closure and rehabilitation spend at Extension Hill of AUD 4 million. The Mid West rail refund, which continues to accrue and come to us, of AUD 2 million. Interest and other income of AUD 2 million and corporate and admin costs of AUD 4 million. We did have an AUD 25 million positive working capital inflow just relating to the timing of receipts and payments. Turning now to Koolan Island operations in a bit more detail. For mining and production, as we've mentioned, the focus is on completing the overburden stripping phase to set up the site for significantly higher ore sales and reduced costs from later this year onwards. We remain on track to meet that target, despite material movement being impacted in the quarter by extensive rainfall and associated lightning interruptions.
We received over one meter of rain in the March quarter, which is obviously pretty extensive. Since the start of this wet season up in the Kimberley, we have received more than 1.8 m of rain, making it the heaviest wet season ever under Mount Gibson ownership since 2007. Total material movement was 4.4 million tonne. Ore production was less impacted, totaling 260,000 tonne, given production was sourced primarily from the upper western end of the main pit, which is less prone to the wet weather interruptions, although it is more variable in quality. Positively, waste stripping rates have increased in recent weeks as the weather has improved, and we expect further gains as we enter the dry season.
We finalized the geotechnical ground support plan for the upper footwall in the main pit to enable us safely to access the high-grade ore zones in the western floor of the main pit later this year. So far, we've engaged specialist contractors, and they've been mobilized to the site this month. The program is expected to cost approximately AUD 15 million over the next six months. The program will progressively allow for safe mining access to the high-grade western floor of the main pit to be opened up. In the near term, medium-grade ore will continue to be sourced from the upper western and eastern ends of the main pit. The first phase of work on the crusher upgrade project, which is estimated to cost us AUD 20 million, is progressing well, with the upgrade designed to ensure efficient processing of significantly greater volumes of high-grade ore from later this year.
The work is being phased to ensure we retain crushing capacity as required over coming months until commissioning of the new circuits in the September quarter. From a cash flow perspective, Koolan generated an operating cash flow of AUD 7 million in the quarter before capitalized advanced waste stripping investment of AUD 35 million, and the other capital projects, primarily the crusher upgrade of AUD 6 million. Site cash costs reflecting the sales and not capturing the ship that was deferred at the month end were AUD 102 FOB per ton sold, and that's before the waste stripping and capital upgrade projects. Unit costs were obviously, as I mentioned, skewed by that delayed shipment. Cash cost guidance for Koolan for the year of AUD 70-AUD 75 per ton sold remains in place.
Turning to our Mid West operations, our focus has been on the development of the Shine iron ore project, which is located 85 km north of the now-closed Extension Hill mine site. Production from Shine is targeted at 1.5 million tonne per annum for an initial two-year period. There is the potential for a further two years if conditions remain supportive. Cash costs at Shine are anticipated to average between AUD 65 and AUD 70 per ton FOB before royalties, with the average iron grade around 59% Fe. We will have both fines and lump products. The site team's made very good progress to date. Work has accelerated in the last couple of months. We're on target to commence sales early in the September quarter. The construction activities on site are well advanced. Mining commenced during March, ahead of our schedule.
We've so far spent approximately AUD 12 million of the estimated AUD 17 million-AUD 20 million capital cost. Of that AUD 12 million, AUD 11 million was spent during the March quarter. That's obviously when activities accelerated. We'll be investing about AUD 15 million in pre-production and inventory build in the current June quarter. In the last week, we've commenced the extraction of the initial ore from the crest of the deposit. In parallel with the site work, we continue to progress the key commercial arrangements, including potential alternatives to the base case transport plan, which is to truck ore by road to our existing storage facilities at Geraldton Port. If you recall, we've made a living for many years in the Mid West of trucking and using rail through to the Geraldton Port facilities.
Meanwhile, rehab of the closed Extension Hill site is advancing in line with the closure plan, and redeployment of personnel and equipment to Shine has been undertaken as appropriate. We expect a reasonable proportion of the existing AUD 9 million closure provision, and that was the provision at December 31, to be incurred over the next 12 months. While no sales were recorded in the Mid West business in the quarter, we did accrue AUD 2 million for the ongoing rail refund credit that I mentioned before. Regarding prices, I wanted to say a few words, which obviously continues to be quite incredibly strong. The average Platts 62% Fe CFR Index fines was $167 per dry metric ton for the quarter, and that was up from $134 in the prior quarter.
The Koolan medium-grade fines, and we're obviously selling lower-grade material whilst the overburden program is done, achieved an average realized price of $106 FOB after penalties. That reflects that lower grade of 60% average in the quarter, which is a function of the stripping program, as I mentioned. Despite the currently reduced shipment volumes, these iron ore prices do continue to have a significant benefit in reducing the net investment that we're required to make to complete the Koolan Island overburden stripping program, as well as indicating for us, in respect of Shine, a much stronger economic outcome from that operation. In relation to guidance for the 2021 financial year, we've maintained group ore sales at 2.8 million-3.3 million tonne. Koolan Island, as we've mentioned, is expected to contribute somewhere around 1.8 million tonne of fines products.
Group cash cost guidance for the financial year remains at AUD 65- AUD 70 per ton FOB, and that's before the investments we're making at Shine for the development of that project and for the Koolan Island overburden stripping and capital improvement projects. That last bit primarily being the crusher upgrade. Koolan Island site cash costs are anticipated to average AUD 70-AUD 75 per ton sold FOB, excluding the capital investments I just mentioned. In closing, while the quarter presented quite a few challenges, particularly with the heavy wet season in the Kimberley region, we progressed the scheduled overburden and capital upgrade programs, and we're now moving ahead rapidly with the development of the Shine project out in the Mid West.
This progress has maintained our position for significantly improved financial performance in the second half of this calendar year. That's obviously our real focus as our investments in the first half enable stronger sales and cash flows to be achieved. On that note, Bethany, I hand back to you for any questions that anyone may have.
Thank you, Peter. Institutional guests are now invited to ask questions by pressing star one on your telephone keypad now. You will hear a tone as you join the queue. Please listen for your name, and I'll introduce you through to ask your question. Our first question is from Paul McTaggart from Citigroup. Please go ahead, Paul.
Good morning, Peter.
Hey, Paul.
How are you going? We just want to get a bit more detail on the AUD 15 million that you need to spend in terms of the footwall work.
I'm really trying to get a sense of how confident you are that it's only going to be AUD 15 million, and whether we're going to see any kind of impacts or disruptions to mining as a result of that work in the course of the period ahead. It's a shame, obviously, we've got this window while iron ore prices are very high. Maybe if you can just give us a sense on exactly what's going to happen there.
Sure. Paul, as you know, the footwall works we're doing is all about safety and the future of the operation in that part of the pit. It arose from the rockfall that we had in the upper part of that footwall in late October, early November last year. We've made estimates, and we've obviously built those estimates in conjunction with a specialist contractor who's now on site, for what we think that work will be, given the design of where the bolting needs to occur on that footwall. It's difficult to precisely estimate because, of course, as we go through and we get experienced with that bolting program, which of course we've done for many years from the base of the pit floor, so there's nothing new about the way that works done.
Upper work higher up on the pit floor may take a little bit of time to become efficient with. We are using a very good contractor who does this in a whole range of applications, including mining. That's our best estimate for the moment. Of course, if we could do it, beg your pardon. If it takes longer, it will become more expensive. We're not sure it will become majorly more expensive. The main issue for us is moving through that program over the priority areas on the footwall so that in a phased way, we can access the area underneath that western end levels.
Okay. Thank you, Peter.
Thank you, Paul. Our next question is from John Scoufis from Macquarie. Please go ahead, John.
Hi, guys.
Hi, John.
Just looking at the satellite options around Koolan Island. Could you give us a bit more color on that and what work's going in there around the satellite bits?
Sure. John, as you know, there are some deposits that we've mined previously, and there are one or two that we are looking at the potential to reaccess. One of those is called Acacia East, if that's the case, we'll be able to blend that material in with the material from the main pit, which is what we did many years ago. In relation to satellite deposits that have not been mined at this point, there's one in particular called Mangrove, which sits along the strike to the east of the main pit. We have worked with the traditional owners in the last few months, for heritage clearance and ground clearance of that area. Even though it has been cleared before, we've taken a pretty robust approach with the traditional owners to make sure that there are no issues, that appears to be the case.
That is scheduled for some drilling this dry season. In addition, there are other deposits, and there is one of which called Coral Trout, where we are doing the same with the traditional owners and seeking through the heritage clearance process to be able to do some drilling there. Both of those areas do have historic drilling, so we do know a little bit about the mineralization, but for mine planning purposes, we would be needing to put an additional program in this year.
Excellent. Thanks, guys. Just over at Shine, I'm just wondering, just for clarity, is the rail refund impacted by the development of Shine at all or coming out of Shine, or is that completely separate?
Completely separate, John. The rail refund relates to the arrangements we previously had at Extension Hill. They don't get impacted by Shine.
Okay. Excellent. Thanks, guys.
Thank you, John. If any other institutional guests would like to ask a question, press star one on your telephone keypad now. Thank you, Peter. It seems we have no further questions at this time. I'll now hand back to you. Thank you.
All right. Thank you, Bethany, and thanks all for listening in. If anyone does have additional queries, then you know where to reach out to us at Mount Gibson. Have a good day. Thank you.