EXHIBIT 10.21

Form of

NET SMELTER RETURN
ROYALTY AGREEMENT

This Agreement (the "Agreement") is entered into on _________ __, 2008, by and
among Minera Milenium S.A. de C.V., a corporation duly organized under the laws
of the Republic of Mexico (hereinafter referred to as "Minera"), [NEWCO], a
corporation incorporated under the laws of _________ ("NewCo") and AURELIO
RESOURCE CORPORATION, a Nevada corporation (hereinafter referred to as
"Aurelio"). Each of Minera, NewCo and Aurelio are referred to herein as "Party",
and collectively herein as the "Parties".

NewCo acquired all of the outstanding capital stock of Bolsa Resources, Inc., an
Arizona corporation, from Aurelio under a certain Stock Purchase Agreement
between Aurelio and the NewCo, dated September __, 2008 (the "Stock Purchase
Agreement"). Under the terms of the Stock Purchase Agreement, Aurelio agreed to
cause Minera to grant to NewCo in exchange for a cash consideration payable to
Aurelio a net smelter return royalty from the minerals product derived form
certain real property assets owned and/or leased by Minera.

This Agreement contemplates the transaction and terms and conditions by which
and the circumstances in which Minera grants to NewCo in exchange for a cash
consideration payable to Aurelio the net smelter return royalty from the
minerals product derived form certain real property assets owned and/or leased
by Minera and in which Minera, Aurelio and NewCo have the right to convert the
net smelter return royalty granted hereunder into shares of Minera or Aurelio,
as the case may be, in accordance with the term of this Agreement.

Now, therefore, in consideration of the premises and the mutual promises herein
made, and in consideration of the representations, warranties, and covenants
herein contained, the Parties agree as follows.

1. Definitions. The following terms shall have the following meaning for
purposes of this Agreement:

"Affiliate" has the meaning set forth in Rule 12b-2 of the regulations
promulgated under the Securities Exchange Act of 1934, as amended.

"Cash Consideration" shall have the meaning set forth in Section 2 below.

"Concentrates" means the product derived from Crude Ore after waste materials
have been removed through leaching, milling or other beneficiation.

"Crude Ores," whether singular or plural, shall mean all ores, metals, Minerals
which Minera either (A) mines, extracts, or otherwise recovers (including by in
situ methods) from the Gavilanes Property and sells or delivers to a processing
plant for physical or chemical treatment, or (B) treats in place on the
Gavilanes Property by chemical, solution, or other methods; said term shall also
include all Mineral-bearing solutions, natural or introduced, recovered by
Minera from the Gavilanes Property and sold or delivered for processing by
Minera, and all Mineral and non-mineral components of all such materials and
solutions.

"Extraction Taxes" means sales, use, gross receipts, ad valorem, severance, any
taxation on the net proceeds of mining operations and other taxes payable in
respect to severance, production, removal, sale or disposition of the Crude Ore
or Concentrates, but excluding any taxes on net income.

"Gavilanes Property" shall mean the real property rights and interests described
in Annex 1 attached hereto and incorporated herein by this reference, and any
and all amendment, substitutions or replacements of the concessions on the
referenced real property in which Minera or any Affiliate of Minera has any
right, title or interest.

"Minerals," whether singular or plural, shall mean any and all mineral
substances of any nature, metallic or non-metallic. The term "Minerals" shall
not include oil, gas, or other liquid or gaseous hydrocarbon or geothermal
substances.

"Proceeds" means the sum actually received by Minera during each calendar
quarter from for the sale of Crude Ore or Concentrates produced from the
Gavilanes Property during each calendar quarter.

"Processing Costs" means either (a) the amounts actually incurred by Minera for
leaching, milling, treating, processing or other beneficiation, including
transporting, sizing and crushing of the ores, where such services are performed
by a party other than Minera and including assaying and sampling costs and
including penalties, if any incurred, or (b) if such operations are carried out
by Minera, the charges, cost and penalties, if any incurred, for such
operations, including transportation, which Minera would have incurred if such
operations were carried out in facilities not owned or controlled by Minera and
then offering comparable custom services for comparable products or on
comparable terms; provided, however, that in all cases "Processing Costs" shall
not include Transportation Costs

"Transportation Costs" means the expenses and charges actually incurred by
Minera in transporting the Crude Ore or Concentrates from mine to mill, smelter,
refinery or other place of sale. Such expenses shall include, but not be limited
to, freight, shipment insurance, handling, port, delay, demurrage, lighterage,
tug, forwarding costs and transportation taxes.

Reference to dollar amounts in this agreement shall refer to United States
dollars.

2. Net Smelter Return Royalty. As of the date hereof, for a cash consideration
of $2,000,000 (in words: US Dollars Two Million), payable by NewCo to Aurelio at
the closing of the transaction contemplated by the Stock Purchase Agreement by
wire transfer or delivery of other immediately available funds (the "Cash
Consideration"), Minera does hereby remise, release, and forever quitclaim unto
Newco its successors and assigns, a production royalty (the ea"Minera NSR") of
three percent (3%) of the Net Smelter Returns(as herein defined) from all Crude
Ores and Concentrates mined or otherwise recovered and removed from mineral
claims on the Gavilanes Property. The Net Smelter Return on Crude Ore or
Concentrates derived and sold by Minera from the Gavilanes Property shall be
determined as follows:

(a) Sale of Crude Ore or Concentrate to Third Party. If Crude Ore or
Concentrates are sold by Minera to a third party that is not an Affiliate of
Minera, the Net Smelter Returns shall mean the Proceeds received from such sale
by Minera, less, to the extent borne by Minera, sales and brokerage costs,
Transportation Costs, Processing Costs and Extraction Taxes. Such Crude Ore or
Concentrates shall be deemed sold at the time the Proceeds are received by
Minera.

(b) Sale of Crude Ore or Concentrate to Affiliate. If Crude Ore or Concentrates
are sold or transferred by Minera to an Affiliate, they shall be deemed sold by
Minera at the time of delivery to the Affiliate, and the Net Smelter Returns
shall mean an amount equal to that which would have been received by Minera from
a bona fide third party purchaser in an arms-length transaction for an identical
product less Transportation Costs, Processing Costs and Extraction Taxes
incurred by Minera.

(c) Retainage of Crude Ore or Concentrate. If Concentrates are retained by
Minera for further smelting, refining, precipitation or other additional
processing by a third party that is not an Affiliate of Minera at a site that is
not located or adjacent to or on the Gavilanes Property, such Concentrates shall
be deemed sold by Minera at the time such Concentrates are delivered to the
smelter, precipitation plant or other facility for further processing or
refining, and the Net Smelter Returns from such Concentrates shall be deemed to
be an amount equal to that which would have been received by Minera from a bona
fide third party purchaser in an arms-length transaction for an identical
product less Transportation Costs, Processing Costs and Extraction Taxes
incurred by Minera.

3. Payment of Royalty. The obligation to pay the Minera NSR royalty shall accrue
upon the actual or deemed sale of the Crude Ores or Concentrates subject
thereto. Payment of the Minera NSR shall be made on or before the last day of
April, July, October, and January ("Payment Dates") of each year for royalty
obligations that accrued during the preceding calendar quarter of Crude Ore or
Concentrates actually produced during that calendar quarter. Payment for any
deemed sale (i.e., through forward sale, loans, futures trading, etc.) of any
Crude Ore or Concentrates during a calendar quarter shall be made on the Payment
Date following the calendar quarter during which production of Crude Ore or
Concentrates actually occurs. Each Payment shall be accompanied by a statement
showing weights and values of mineral substances recovered from the Crude Ore
and Concentrates produced from the Gavilanes Property during the period for
which payment is made, the Proceeds received or the value of the deemed sale of
such Crude Ore and Concentrates and the amount of the charges, costs and taxes
deductible therefrom. If no written objection is made by Aurelio to the
correctness of the statement within sixty (60) days from the date thereof, such
statement shall be deemed conclusively to be correct and such royalty payment
sufficient and complete.

4. Disputes. In case of any dispute or question as to the ownership of any
royalty interest, payment of any part thereof to be made by Minera under this
Agreement, Minera may deposit any amount otherwise due to Newco in escrow until
the dispute is finally resolved. Minera may credit all costs and expenses,
including attorney's fees, it incurs by reason of such dispute or question
against all amounts otherwise due to Newco only in the event Minera prevails.

5. Waste Rock, Spoil and Tailings. The ore, mine waters, leachates, pregnant
liquors, pregnant slurries, or other products or compounds of Mineral Substances
mined or extracted from the Gavilanes Property shall be the property of Minera
subject to the Minera NSR as provided herein. Minera shall not be liable for
mineral values lost in mining or processing employing sound practices. The
Minera NSR shall be payable on all mineral substances recovered both prior to
and after the time waste rock, spoil, tailings, or other mine wastes and residue
are first disposed of as such, and such waste rock, spoil, tailings or other
mine wastes and residue shall be the sole property of Minera. Minera shall have
the sole right to dump, deposit, sell, dispose of, or reprocess such waste rock,
spoil, tailings, or other mine wastes and residues, and Aurelio shall have no
claim or interest therein or to proceeds or minerals values recovered therefrom.

6. Weighing, Measuring and Sampling. Minera shall at all times production is
occurring upon the Initial Minera Real Property Assets accurately weigh, measure
and sample in accordance with customary industry practices for precious metals
mines, all Crude Ore or other material including products developed from ore or
other material, and all Concentrates, to the end that accurate and complete
records and reports are made and retained to ascertain the quantity of ores and
minerals recovered and removed from the Initial Minera Real Property Assets. In
determining whether "customary industry practice" is being employed,
consideration shall be given to whether the ore body from which production is
occurring is a placer deposit or other type of deposit. If production is from a
placer deposit, then the grade and weight of concentrate developed at the
gravity separation facility shall be determined and recorded, and the grade and
weight of all ore produced in the onsite refinery shall be determined and
recorded, and the grade and weight of slag recovered from the onsite refinery
shall be determined and recorded, and the grade and weight of settled ounces at
the final refiner shall be determined and recorded; provided, however, that
Minera shall not be required to determine the grade and weight of concentrate
developed at the gravity separation facility if it makes a demonstration to
Newco from which it can be reasonably concluded, taking into consideration all
existing facts and circumstances, that the samples taken would not be
representative of the true grade and weight of the concentrate. In the event
Minera makes the demonstration mentioned above, Newco shall have the right to
take such samples at its own expense and on a basis that does not interfere with
Minera's business or operations. Newco shall provide Minera with a copy of all
sampling information so derived. Newco shall have the right, upon reasonable
notice at all reasonable times, to inspect all records and reports mentioned
herein, the real property and the operations being conducted thereon, so long as
such inspections do not unreasonably interfere with Minera's business or
operations.

7. Additional Land Purchase or Lease. To ensure the mining rights on the
Gavilanes Property will not interfere with adjunct mining rights and other real
property usage, Minera shall use its commercial efforts to purchase any
additional land adjunct to the Gavilanes Property that it deems appropriate to
ensure those mining rights.

8. Additional Funding of Minera. As long as the Minera NSR (or after its
conversion the Minera Preferred Stock) is outstanding, NewCo and its affiliates
shall have the first right to provide any additional funding (debt and/or
equity) to Minera and shall further have the first right to make an offer if (i)
Minera decides to sell the rights in the Gavilanes property and/or substantially
all of its Mexican assets or (ii) Aurelio decided to sell Minera .

9. Conversion of Minera NSR. The Minera NSR shall be convertible as follows:

(a) Conversion in Case of Minera IPO. Automatically at fair market value for
shares of common stock of Minera immediately prior to an Initial Public Offering
of shares of common stock of Minera (a "Minera IPO");

(b) Optional Conversion in case of Strategic Minera Transaction. At the option
of Minera, at fair market value for shares of common stock of Minera,
immediately prior to a sale, transfer or license of all or substantially all of
the assets of Minera for cash or publicly traded securities, or a sale of equity
interests for cash or publically traded securities, or a merger, reorganization
or other transaction resulting in the stockholders of Minera immediately prior
to the transaction (on a fully diluted basis) controlling less than the majority
of the voting power of the surviving entity on a fully diluted basis (a
"Strategic Minera Transaction");

(c) Optional Conversion by Newco. At the option of the then holder of the Minera
NSR at fair market value into shares of common stock of Minera immediately prior
to a Strategic Minera Transaction;

(d) Optional Conversion upon Commencement of Mining Production. At the option of
Minera, at fair market value for shares of preferred stock of Minera (the
"Minera Preferred Stock") (the fair market value of the Minera NSR divided by
the number of Minera Preferred Stock issued in accordance with this Section 9(d)
hereinafter the "Original MineraPS Issue Price") upon commencement of commercial
mining production from any of Gavilanes Property (the day a conversion under
this Section 9(d) occurs the "Minera Conversion Day"). The Minera Preferred
Stock will have the following attributes:

(i) The Minera Preferred Stock will be entitled to a cumulative annual preferred
dividend equal to a six percent (6%). Upon conversion of the Minera Preferred
Stock in accordance with Section 9(d)(iv) below, Minera shall have the right to
convert any unpaid accumulated dividend on the Minera Preferred Stock that is
being converted into shares of the same class of shares of Minera or Aurelio, as
the case may be, into which the Minera Preferred Stock is converted;

(ii) The Minera Preferred Stock will vote with all other shares of the Minera on
an as converted basis as a single class on all matters;

(iii) Each share of Minera Preferred Stock will have 1 time liquidation
preference equal to the Original MineraPS Issue Price;

(iv) Subject to any adjustment being made to the conversion rate following any
recapitalization, share split, consolidation or similar events (collectively
"Recapitalization Events") and/or the operation of the anti-dilution provision
set forth in subsection (v) of this Section 9(d), the Minera Preferred Stock
will be convertible as follows:

(A) At the option of Newco immediately prior to a Minera IPO or Strategic Minera
Transaction into an equivalent number of shares of common stock of Minera;

(B) At the option of the then holders of the Minera Preferred Stock at any time
into an equivalent number of shares of common stock of Minera;

(C) At the option of the then holders of the Minera Preferred Stock at any time
pro rata into registered shares of common stock of Aurelio; and

(D) At the option of the then holders of the Minera Preferred Stock pro rata for
shares of preferred stock of Aurelio at any time after the fifth (5th)
anniversary of this Agreement; the shares of preferred stock of Aurelio so
issued shall have the identical rights as set forth under Section 9(d)(i) -
(iii) above and Section 9(d)(v) below and shall be convertible at the option of
its holder at any time into an equivalent number of shares of common stock of
Aurelio; and

(v) In the event that Minera during the twelve (12) months following the
issuance of the Minera Preferred Stock issues additional securities at a
purchase price (after adjusting for any Recapitalization Events) less than the
Original MineraPS Issue Price (the "Existing MineraPS Conversion Price"), the
Original BPS Issue Price shall be adjusted in accordance with the following
formula:

CP2 = CP1 * (A+B) / (A+C)

with

CP2 = New MineraPS Conversion Price,

CP1 = Existing MinserPS Conversion Price in effect immediately prior to new
issue,

A = Number of shares of common stock of the Minera deemed to be outstanding
immediately prior to new issue (includes all shares of outstanding common stock
of the Minera, all shares of outstanding Minera Preferred Stock on an
as-converted basis, and all outstanding options on an as-exercised basis),

B = Aggregate consideration received by the Minera with respect to the new issue
divided by CP1, and

C = Number of shares of stock issued in the subject transaction,

and the holders of the Minera Preferred Stock shall be entitled free of charge
to the additional Minera Preferred Stock they would have received if the New
MineraPS Conversion Price would have been the Original MineraPS Issue Price at
the time of the issuance of Minera Preferred Stock in accordance with this
Section 9(d).

10. Miscellaneous.

(a) Further Actions. The Parties hereby agree that they will each take such
further action (including the execution and delivery of such future instruments
and documents) as the other Party may request in order to comply with the
interests of the Parties pursuant to this Net Smelter Return Agreement in order
to comply with Arizona law.

(b) Press Releases and Public Announcements. No Party shall issue any press
release or make any public announcement relating to the subject matter of this
Agreement prior to the Closing without the prior written approval of the other
Parties; provided, however, that any Party may make any public disclosure it
believes in good faith is required by applicable law or any listing or trading
agreement concerning its publicly-traded securities (in which case the
disclosing Party will use its reasonable best efforts to advise the other
Parties prior to making the disclosure).

(c) No Third-Party Beneficiaries. This Agreement shall not confer any rights or
remedies upon any Person other than the Parties and their respective successors
and permitted assigns.

(d) Reporting. Minera shall provide Newco bi-annual reports describing progress
of activities at the Gavilanes Property in form and substance reasonably
satisfactory to the parties.

(d) Entire Agreement. This Agreement (including the documents referred to
herein) constitutes the entire agreement among the Parties and supersedes any
prior understandings, agreements, or representations by or among the Parties,
written or oral, to the extent they related in any way to the subject matter
hereof.

(e) Succession and Assignment. This Agreement shall be binding upon and inure to
the benefit of the Parties named herein and their respective successors and
permitted assigns. The Gavilanes NSR shall run with the Gavilanes Property \

(f) Counterparts. This Agreement may be executed in one or more counterparts,
each of which shall be deemed an original but all of which together will
constitute one and the same instrument.

(g) Headings. The section headings contained in this Agreement are inserted for
convenience only and shall not affect in any way the meaning or interpretation
of this Agreement.

(h) Notices. All notices, requests, demands, claims, and other communications
hereunder will be in writing. Any notice, request, demand, claim, or other
communication hereunder shall be deemed duly given if (and then two business
days after) it is sent by registered or certified mail, return receipt
requested, postage prepaid, and addressed to the intended recipient as set forth
below:

If to NewCo: Copy to:

[NEWCO] Buchanan Ingersoll &Rooney PC
[ADDRESS] 620 Eighth Avenue
[ADDRESS] New York, NY 10018
[ADDRESS] U.S.A.
Phone: Phone: +1 (212) 440-4400
Fax: Fax: +1 (212) 440-4401
Attention: Attention: Titus Weinheimer

If to Minera: Copy to:

Minera Milenium S.A. de C.V. Holland & Hart LLP
[ADDRESS] 555 Seventeenth Street
[ADDRESS] Suite 3200
[ADDRESS] Denver, CO 80202
Mexico U.S.A.
Phone: Phone: +1 (303) 295-8493
Fax: Fax: +1 (303) 291-9145
Attention: Attention: Lucy Schlauch-Stark

If to Aurelio: Copy to:

Aurelio Resource Corporation Holland & Hart LLP
12345 West Alameda Parkway 555 Seventeenth Street
Suite #202 Suite 3200
Lakewood, CO, 80228 Denver, CO 80202
U.S.A. U.S.A.
Phone: 303-795-3030 Phone: +1 (303) 295-8493
Fax: 303-945-7270 Fax: +1 (303) 291-9145
Attention: David Johnson Attention: Lucy Schlauch-Stark

Any Party may send any notice, request, demand, claim, or other communication
hereunder to the intended recipient at the address set forth above using any
other means (including personal delivery, expedited courier, messenger service,
telecopy, telex, ordinary mail, or electronic mail), but no such notice,
request, demand, claim, or other communication shall be deemed to have been duly
given unless and until it actually is received by the intended recipient. Any
Party may change the address to which notices, requests, demands, claims, and
other communications hereunder are to be delivered by giving the other Parties
notice in the manner herein set forth.

(i) Governing Law. This Agreement shall be governed by and construed in
accordance with the domestic laws of the State of Arizona without giving effect
to any choice or conflict of law provision or rule (whether of the State of
Arizona or any other jurisdiction) that would cause the application of the laws
of any jurisdiction other than the State of Arizona.

(j) Amendments and Waivers. No amendment of any provision of this Agreement
shall be valid unless the same shall be in writing and signed by all Parties. No
waiver by any Party of any default, misrepresentation, or breach of warranty or
covenant hereunder, whether intentional or not, shall be deemed to extend to any
prior or subsequent default, misrepresentation, or breach of warranty or
covenant hereunder or affect in any way any rights arising by virtue of any
prior or subsequent such occurrence.

(k) Severability. Any term or provision of this Agreement that is invalid or
unenforceable in any situation in any jurisdiction shall not affect the validity
or enforceability of the remaining terms and provisions hereof or the validity
or enforceability of the offending term or provision in any other situation or
in any other jurisdiction.

(l) Expenses. Each of the Parties will bear his or its own costs and expenses
(including legal fees and expenses) incurred in connection with this Agreement
and the transactions contemplated hereby.

(m) Construction. The Parties have participated jointly in the negotiation and
drafting of this Agreement. In the event an ambiguity or question of intent or
interpretation arises, this Agreement shall be construed as if drafted jointly
by the Parties and no presumption or burden of proof shall arise favoring or
disfavoring any Party by virtue of the authorship of any of the provisions of
this Agreement. Any reference to any federal, state, local, or foreign statute
or law shall be deemed also to refer to all rules and regulations promulgated
thereunder, unless the context requires otherwise. The word "including" shall
mean including without limitation.

(n) Incorporation of Exhibits, Annexes, and Schedules. The Exhibits, Annexes,
and Schedules identified in this Agreement are incorporated herein by reference
and made a part hereof.

THE REMAINDER OF THIS PAGE IS INTENTIONALLY LEFT BLANK

SIGNATURE PAGE FOLLOWS

*****

IN WITNESS WHEREOF, the Parties hereto have executed this Agreement on the date
first above written.

MINERA MILENIUM S.A. DE C.V.

__________________________________
By:

Name:

Title:

[NEW CO]

__________________________________
By:

Name:

Title:

AURELIO RESOURCE CORPORATION

__________________________________
By:

Name:

Title:

3930220_3.DOC