Thank you for joining today's teleconference for the release of Mount Gibson Iron's March quarter activities report. Mount Gibson Iron's Chief Executive Officer, Peter Kerr, will be leading the discussions and is joined by Chief Financial Officer, Gillian Dobson, and External Relations Manager, John Phaceas. Mr. Kerr will provide a brief overview, after which there'll be an opportunity to ask questions. Due to time constraints, only institutional participants will be invited to ask a question at that time. A recording of the call will also be available via the Mount Gibson website shortly after the completion of today's teleconference. Please go ahead, Peter.
Thanks, Erica, and good morning all, and thanks for joining us to discuss Mount Gibson's March quarter report. As usual, I'll give a brief overview before handing back to Erica for any questions. The March quarter was the final period for net investment at Koolan Island as the major overburden stripping program nears completion. This activity, as we all know, has been the primary draw on our cash reserves for the last year. We're now seeing increasing production rates of high-grade ore, and the waste-to-ore stripping ratio has substantially declined. In combination, these two factors are fundamental for us to generate substantial cash flows over the next five years. The focus at Koolan Island is now on increasing the high-grade ore production from the Main Pit ore zones as the overburden stripping requirements continue to fall.
Total material movement in the quarter was 3.7 million wet metric tons, which was 15% lower than the prior quarter and reflecting the usual adjustments for the wet season and the reduced stripping ratio, while the ore production doubled to 325,000 tons. Ore extraction rates have been increasing steadily since we regained mining access to the initial high-grade ore zones in the Main Pit in February, and waste material movement has been reducing commensurately. In addition, ground support works on the upper western footwall, comprising the wagon-mounted drilling, bolting, and grouting activities, were advanced to the point where mining could safely proceed on the pit floor below each completed area.
As noted in the quarterly report, ground support drilling and bolting has now been completed over approximately 70% of the upper western footwall zones scheduled for this work, and that extends over the western 1 kilometer of the 2-kilometer-long Main Pit. Work over the remainder of the western footwall is targeted for completion in the September quarter, in line with the mine plan for the underlying mine zones in the floor of the pit. The waste-to-ore stripping ratio is declining as scheduled, and you might recall it was 17 to 1 in the December half year, and in the March quarter, it was a little over 10 to 1. A further reduction is occurring in the current quarter such that the average strip ratio is anticipated to be approximately 5 to 1 for the June half year period.
This improvement in the June quarter will be driven by substantially higher ore production, with Koolan Island sales still targeted at 1.5 million wet metric tons for the 2021/2022 financial year. Sales over the first 9 months totaled 0.64 million wet metric tons, meaning shipments will obviously be heavily weighted to this current June quarter. Going forward, from the middle of this year, we expect the strip ratio to average approximately 1.5 tons of waste for every ton of ore over the next five years of operations at Koolan Island. For the 2022/2023 financial year, we expect the strip ratio to average around 2 to 1, and that will be approximately 3.5 to 1 in the first half of that year and reducing to 1 to 1 in the second half, per our mine plans at this stage.
As noted, ore production for the March quarter totaled 325,000 wet metric tons, which was double the ore tonnage extracted in the prior quarter, which was at the height of the overburden stripping program. Ore sales totaled 238,000 wet metric tons, and sales are now increasing. The grade of the ore sales also rose substantially from under 58% FE in the prior half year to 62.8% FE in the March quarter as we blended in some stocks of medium-grade material with the newly mined high-grade ore from the Main Pit. Sales grade is expected to increase to the ore reserve grade of 65% FE around the middle of this year. In terms of other activities on the island, the crusher upgrade was concluded in December, and commissioning works are well underway as the ore throughput increases.
Tropical Cyclone Anika interrupted activities in late February and early March, notably due to the temporary evacuation of some site personnel for several days. Rainfall this wet season totaled 1.2 meters, and numerous rain and lightning delays were encountered, but it wasn't quite as bad as the previous wet season where the total rainfall was 1.85 meters. The seawall also continues to perform to design as expected. Unit mining, logistics, and administration costs, including all transport charges, were AUD 12.07 per ton of ore and waste moved, so that's per total material moved in the quarter. That compared with AUD 10.89 in the prior quarter, reflecting the reduced total material movement and the impacts of the wet season and some COVID interruptions. Productivity and commercial initiatives to reduce these costs are underway.
Obviously, the unit cash cost per ton of ore shipped are expected to reduce significantly as total mining expenditure declines and the ore shipment volumes increase. From a cash flow perspective, the net investment in the quarter was lower than previously, halving to AUD 38 million from the prior quarter. This included overburden stripping investment of AUD 29 million and other capital investments, including the upper footwall ground support program that I just spoke about of AUD 5 million. Operating cash flows are anticipated to become positive in the June quarter, and increasingly so thereafter, as total material movement levels reduce and the high-grade ore shipment volumes rise. In relation to COVID, I just wanted to make a few comments regarding current and possible impacts. We, so far have not been immune to the workforce impacts from COVID, but we fortunately to date avoided substantial disruptions.
Similar with other miners in WA, we've enhanced our screening, testing, and transmission mitigation measures, and the positive response of our employees and contractor workforce is acknowledged. However, the potential impacts of COVID on our workforce is a risk to our near-term operational productivity, in particular, given the community transmission in WA is now at record levels. In recent weeks, Koolan Island has experienced COVID-related absenteeism of between 6% and 10%, and that's due either to individuals being unable to work because they've contracted COVID or because they're close contacts with someone with COVID and are required to isolate under the WA rules. Elsewhere in the business, in the Mid West, the Shine site remains in a low-cost care and maintenance state, and we're monitoring the market conditions for a potential restart.
At this time, product discounts for medium-grade material as well as heightened shipping freight rates from Geraldton Port remain an obstacle for a near-term restart of the operation. Mount Gibson has also received multiple inquiries relating to its infrastructure in the Mid West, in particular for rail sidings and storage sheds in Geraldton Port, and we're already receiving some income from third parties for some initial arrangements that we've structured. Our discussions are in progress regarding further interim arrangements for utilization of spare capacity that we have within those infrastructure assets. In relation to exploration, as we've mentioned previously, we've also commenced activities on our increased footprint around the former Tallering Peak mine and areas to the north of that area, which is about 150 kilometers northeast of Geraldton. We see in this area attractive prospectivity for base metals mineralization.
In the March quarter, detailed field mapping and lag sampling was undertaken at two key prospects, with assay results from those samples expected during the coming weeks. Interpretation of airborne electromagnetic survey data generated over prospective areas in December is also nearing completion, and that's with a view to undertaking some drilling around the middle of this year. Finally, in relation to realized pricing and cash flow for the quarter, our sales revenue totaled AUD 26 million FOB as we report. All of our numbers are in FOB terms. With the Koolan Island fines realizing an average price after penalties and shipping freight charges of $81 per ton FOB. Shipping freight from Koolan to China averaged approximately $19 per ton for the quarter.
At current prices, a Koolan Island fine shipment grading around 63% iron, which is what we've been selling recently, is worth approximately AUD 11 million FOB before royalties. The company's cash and investment balance was AUD 92 million at the end of the quarter, and the movement over the quarter reflected the net investment at Koolan of AUD 38 million, interest and other income of AUD 4 million, and their net corporate exploration and minor rehabilitation costs of AUD 4 million, as well as working capital movements of AUD 12 million. In summary, we're now starting to see the anticipated positive changes at Koolan Island, where rising high-grade ore production and reducing waste to ore strip ratios will generate substantial positive cash flow over the remainder of the operation's five-year mine life.
This is strategically advantageous for us, given the increasing importance of high-grade iron ore feedstocks, notwithstanding the iron ore price fall we've had overnight, which, hopefully at this stage, we see as a temporary thing, given it's a COVID-linked issue for Chinese economics. It's important for us in terms of grade, in boosting steel mill productivity and reducing carbon intensity of steel production. High-grade ores continue to enjoy a solid premium over lower grade ores, and this is expected by us to remain the case for medium and longer term. With that, I'll hand back to you, Erica, for any questions that anyone may have.
Thank you. The question and answer session has now commenced. Institutional guests are now invited to ask a question by pressing star one on their telephone keypad now. You will hear a tone as you join the queue, and please wait for me to introduce you through to call. That is star one on your telephone keypad now if you would like to ask a question. We don't seem to have any questions coming through at this time. We're more than happy to give it another minute or so. That's star one on your phone keypad if you would like to ask a question.
Erica, unless there are any questions, we're happy to end it there because the analysts and investors and shareholders who follow us can easily pick up the phone to us, and we can respond to any queries that might come in due course.
Absolutely. No worries, Peter. In that case, I'll close the question and answer session down now.
Great. All right. Thanks, all, and have a good day.
Thank you. That now concludes today's teleconference. We appreciate you attending, and enjoy the rest of your day.