MAINSTREAM MINERALS CORPORATION 
By August 23rd, 2011 – Winnipeg, MB
Mainstream Minerals Corporation (TSX.V: MJO) (“Mainstream”) is pleased to provide an update on its recent exploration activities on the Bobjo Mine and Slate Lake properties. In June, Mainstream contracted Mount Morgan Resources Ltd. to complete a channel sampling program at the Bobjo Mine project. The channel samples targeted previously untested outcrops with quartz veins, lenses and veinlets with the intention of assessing the potential for gold mineralization outside of the immediate Bobjo Mine environment. There were a total of 66 samples that were analyzed from the 33 meters of channel sampling. The program was very successful with multiple high-grade gold assays received from a series of 0.5 meter channel samples. The channel samples contained quartz veins +/- bedrock. Results indicate significant gold potential exists outside of the actual Bobjo Mine shaft. Assay results ranged from <.03 g/t Au up to a high of 87.53 g/t Au. A table highlighting the best samples is given below:
Sample Number | Sample Location | Description | Au g/t |
| BJ11-56 | 15 U 526236 5661196 | Quartz | 87.53 |
| BJ11-28 | 15 U 526256 5661160 | Quartz | 50.79 |
| BJ11-62 | 15 U 526234 5661207 | Quartz | 39.59 |
| BJ11-26 | 15 U 526258 5661155 | Quartz and bedrock | 32.48 |
| BJ11-29 | 15 U 526248 5661158 | Quartz | 32.41 |
| BJ11-25 | 15 U 526254 5661153 | Quartz | 21.47 |
| BJ11-27 | 15 U 526258 5661155 | Quartz and bedrock | 18.93 |
| BJ11-22 | 15 U 526258 5661154 | Quartz and bedrock | 16.98 |
| BJ11-61 | 15 U 526234 5661207 | Quartz | 11.13 |
| BJ11-09 | 15 U 526289 5661129 | Quartz | 7.70 |
| BJ11-03 | 15 U 526288 5661120 | Quartz and bedrock | 5.61 |
| BJ11-60 | 15 U 526235 5661206 | Quartz | 4.72 |
| BJ11-59 | 15 U 526235 5661201 | Quartz | 4.29 |
| BJ11-08 | 15 U 526289 5661129 | Quartz | 3.82 |
| BJ11-01 | 15 U 526283 5661123 | Quartz and bedrock | 3.16 |
| BJ11-30 | 15 U 526249 5661168 | Quartz and bedrock | 2.85 |
| BJ11-05 | 15 U 526288 5661130 | Quartz | 2.62 |
| BJ11-36 | 15 U 526251 5661153 | Quartz | 2.06 |
| BJ11-63 | 15 U 526234 5661207 | Quartz | 1.75 |
The channel samples were processed and analyzed by TSL Laboratories located in Saskatoon, Saskatchewan. TSL Laboratories as an ISO-Certified laboratory performed the gold assays and a multi-element scan of the sample set. Two kinds of analyses were used. One is a gold fire assay with gravimetric finish and the second a multi-element scan. The multi-element scan provides information for a wide range of elements at very low detection limits. This analysis is used to determine whether there are any unusual “pathfinder” elements that might be used to indicate the presence of gold mineralization. Analysis is by ICP-MS. The gold assay is based upon 60 grams of rock after it has been crushed and powdered. A serious gold nugget effect in the mineralized samples is documented from metallic screen assays and indicates significant specific gravity differences between gold-bearing mineralization and the host rock. The high-grade gold assays suggest the likely presence of native gold.
Mainstream President and Chief Executive Officer, Michael Romanik, says: “We are very excited with the recent assay results since they are from previously unrecognized zones of gold mineralization. There are many other outcrops that remain untested and will be followed up in the next round of exploration. We firmly believe that the Bobjo Mine project has excellent potential for finding more high grade gold and will be an exciting project for Mainstream going forward.”
Mainstream is reviewing the drill logs from the 32 holes that were drilled in 2007-2009 as well as the core logs from the 11 holes totaling 4,580 meters that were drilled by Premier Gold Mines Limited in late 2010 and early 2011. The company plans to incorporate the most recent channel sample results with the data from the drill logs in order to formulate exploration plans for the fall of 2011.
In June 2011, Mainstream staked 9 claims tying the Fly Lake – Bobjo Mine – Slate Lake projects together. This will enable the company to transfer future assessment work freely between the three projects giving the company greater operational flexibility going forward.
Mount Morgan Resources Ltd. of Winnipeg, Manitoba also completed the second and final phase of the mobile metal ions (MMI) soil sampling program on the Slate Lake property. The survey detected elevated Au levels at several locations. Rock chip samples were collected in the vicinity of MMI soil geochemical gold anomalies outlined in the first phase. Two of the seven rock chip samples returned elevated gold content values. In particular, sample SL11-05 which assayed 0.14 g/t Au strongly confirms the presence of gold-bearing mineralization on the Slate Lake property. It also suggests that MMI soil geochemical surveys were effective in delineating follow-up gold exploration targets.
Interpretation of the mobile metal ions geochemical survey results was undertaken and an updated MMI results report dated July 18th, 2011 was prepared by Mount Morgan Resources Ltd
Over the summer, National Instrument 43-101 technical reports were completed on the Hudson Patricia Mine and Rowan Lake properties. The two reports recommended at least $500,000 of work on each property in the next phase of exploration. The reports were commissioned to provide the company with a background of all historical work that was performed on both properties. The reports themselves may prove to be useful in attracting potential joint-venture partners or as a qualifying transaction for Capital Pool Companies.
Due to the forest fire situation and lack of lodging, the prospecting / sampling program that was scheduled for the Birch Lake property has been pushed back to the fall of 2011. The Birch Lake property is comprised of two non-contiguous groups of mining claims covering a total of 1,440 hectares. The southeastern claim group (four claims covering 704 hectares) sits between, and contiguous to, Gold Canyon Resources Inc.’s Springpole gold project and Pelangio Exploration Inc.’s Birch Lake property. The northeastern claim group (six claims covering 736 hectares) is contiguous to Pelangio Exploration Inc.’s Birch Lake property. The planned construction of an all season road leading up to Gold Canyon’s Springpole deposit could greatly reduce exploration costs for all companies involved in the Birch Lake / Casummit Lake area.
Mark Fedikow, P.Geo is the Qualified Person pursuant to National Instrument 43-101 and has reviewed and approved the technical disclosure in this press release.
About Mainstream Minerals
Mainstream Minerals Corporation is a mineral exploration and development company focused on precious metal mining properties with economic potential, with the aim of bringing such properties to commercial production. With a portfolio of six projects located in the Birch Uchi Greenstone Belt, Red Lake Mining District, the company is well positioned to take advantage of the resurgence of exploration and development activities in this prospective belt located 80 kilometres due east of the main Red Lake Greenstone Belt. These six projects cover an area of approximately 27,000 acres and host several known gold occurrences and past producing mines. Other projects include the Rowan Lake project on the Cameron Lake-Pipestone Fault in the Kenora Mining District, the West Keefer and Price Claims located in the West Timmins area in north-central Ontario and the Casa Berardi Claims in northern Québec.
MJO Shares Outstanding: 53,972,130
ON BEHALF OF THE BOARD
Signed “Michael Romanik”
Michael Romanik, President & CEO
(204) 222-0137
info@mainstreamminerals.com
This news release includes certain forward-looking statements concerning the future performance of Mainstream Mineral Corporation’s business, its operations and its financial performance and condition, as well as management’s objectives, strategies, beliefs and intentions. The Company does not intend, and does not assume any obligation, to update these forward-looking statements. Forward-looking statements are frequently identified by such words as “may”, “plan”, “expect”, “anticipate”, “estimate”, “intend” and similar words referring to future events and results. These forward-looking statements represent management’s best judgment based on current facts and assumptions that management considers reasonable. The Company makes no representation that reasonable business people in possession of the same information would reach the same conclusions. All forward-looking information is inherently uncertain and subject to a variety of assumptions, risks and uncertainties, including the speculative nature of mineral exploration and development, fluctuating commodity prices, competitive risks and the availability of financing and as described in more detail in the Company’s recent securities filings available at www.sedar.com. Actual events or results may differ materially from those projected in the forward looking-statements and readers are cautioned against placing undue reliance thereon.
Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.
