Contract

Exhibit 10.13

Effective Date: April 1, 2016

Re: Eos Petro, Inc. Promissory Note

Dear Xx. Xxxxxx:

Reference is made to a promissory note in the principal amount of $30,000 made on November 5, 2015 (the "Note") in favor of Xxxx Xxxxxx, an individual ("Xxxxxx"), made by Xxx Xxxxx, Inc. ("Eos," collectively referred to with Xxxxxx as the "Parties").

You are hereby requested in this letter (this "Letter Agreement") to indicate your agreement to, and acknowledgement of, the following:  The Parties hereby agree that the maturity date of the Note is extended to September 30, 2016.

Please acknowledge your agreement to, and acceptance of, the foregoing by signing this Letter Agreement below.  Please return a signed copy to the undersigned, it being agreed that this Letter Agreement may be executed in counterparts and signatures received by electronic transmission shall have the same effect as original signatures.

Sincerely,

XXXXXXX XXXXXXXX, signing in his individual capacity and as the Chairman and CFO of Eos Petro, Inc., a Nevada corporation

By: /s/ Xxxxxxx Xxxxxxxx

ACKNOWLEDGED AND AGREED TO ON MAY 12, 2016 BY:

XXXX XXXXXX, an individual

By: /s/ Xxxx Xxxxxx

Name: Xxxx Xxxxxx