Micrex Development Corp.: St. Charles Erbium Assays Revised

Micrex (TSX VENTURE:MIX) announces revised results for erbium that were reported
for holes 99-04 and 99-06 in the press release dated April 20, 2010. The
independent assay lab reports that their erbium results were incorrect due to
interference from the sample's matrix elements. The revised assays show trace
amounts of erbium are present, and the erbium values they reported previously
were in error.


Micrex is encouraged that a proper assay method has been developed to ensure
accuracy in the future and to eliminate interference from matrix minerals.


The lab has rerun the tests for all the other rare earths and confirmed that the
April results for them were accurate. The average numbers for the rare earths in
parts per million (ppm) are:




Hole      CeO2      Gd2O3     Nd2O3     Y2O3      Total REE 
99-04     958       271       1003      155       2632      
99-06     875       200       670       108       2057      



The full revised assay results can be viewed at the St. Charles page on the
Micrex web site at www.mixcorp.com.


Magnetite, titanium, apatite and vanadium already provide a solid foundation for
development of the property, and Micrex is confident that the rare earth
elements will have a positive, value added impact on the overall deposit at St.
Charles. 


As a result, Micrex continues to focus its exploration on the Quebec project,
with a view of completing a NI 43-101 report and additional drilling.


This press release has been reviewed by Mr. Michael Dufresne, M.Sc., P.Geol. a
principal of APEX Geoscience Ltd. and the Company's Qualified Person for this
project under the meaning of NI 43-101.


MICREX DEVELOPMENT CORP.

Burmis Magnetite/Titanium Property - St. Charles de Bourget Magnetite/Titanium
Property - Fort Steel Placer Property - Bighorn Gold Mine - Banks Gold Mine -
Mount Royal Gold Mine - Deadwood Gold Mine - Sunburst Gold Property


FORWARD LOOKING STATEMENTS

Certain statements in this news release are "forward-looking statements", which
reflect management's expectations regarding its property and business
operations. All statements other than statements of historical fact contained in
this news release are forward-looking statements. Such forward-looking
statements involve risks and uncertainties, as they reflect management's current
beliefs and are based on information currently available to management. Actual
results may differ materially from those anticipated in the statements made. The
forward-looking statements are expressly qualified in their entirety by this
cautionary statement. The forward-looking statements are made as of the date of
this news release and Micrex assumes no obligation to update or revise them to
reflect new events or circumstances except as expressly required by applicable
securities law. Further information regarding the uncertainties and risks can be
found in the disclosure documents filed by Micrex with the securities regulatory
authorities, available at www.sedar.com.