Exhibit 4.21

edward nathan sonnenbergs

johannesburg cape town durban

150
west street

sandown sandton johannesburg 2196

p o box 783347 sandton south africa 2146

docex 152 randburg

tel +2711 269
7600 fax +2711 269 7899

info@problemsolved.co.za www.problemsolved.co.za

FIRST ADDENDUM TO THE SALE OF BUSINESS AGREEMENT

entered into between

HARMONY GOLD MINING COMPANY LIMITED

and

BUSINESS VENTURE INVESTMENTS NO 1692
PROPRIETARY LIMITED



| |  |                                     |  |                                                                                 
| |  | ----------------------------------- |  | --------------------------------------------------------------------------------
| |  | law | tax | forensics | IP |
africa |  | edward nathan sonnenbergs incorporated        registration number 2006/018200/21



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|1. | INTERPRETATION
|-- | --------------



| | In this Addendum 
| | ------------------



| | 1.1. | Addendum means this first addendum to the Sale of Business Agreement;
| | ---- | -----------------------------------------------------------------------



| | 1.2. | Sale of Business Agreement means the sale of business agreement entered into between the Parties on 20 March 2013; and
| | ---- | ------------------------------------------------------------------------------------------------------------------------



| | 1.3. | unless otherwise defined herein or the context indicates otherwise, words and expressions defined in the Sale of Business Agreement will have the same meanings and any reference to the word clause or
annexure refers to a clause or annexure of the Sale of Business Agreement.
| | ---- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



|2. | INTRODUCTION
|-- | ------------



| | 2.1. | The Parties have agreed to amend the Sale of Business Agreement by making certain amendments.
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| | 2.2. | The Parties have agreed to extend the date for fulfilment of the Condition Precedent contained in clause 4.1.14.
| | ---- | ----------------------------------------------------------------------------------------------------------------



| | 2.3. | The Parties wish to record their agreement in writing.
| | ---- | ------------------------------------------------------



|3. | AMENDMENT
|-- | ---------



| | The | Parties hereby amend the Sale of Business Agreement by deleting the words and numbers 
| | --- | ---------------------------------------------------------------------------------------



| | 3.1. | 1 March 2013 where they appear in clause 2.1.32 and the replacement thereof with the words and numbers 1 April 2013;
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| | 3.2. | R460,600,000 (four hundred and sixty million and six hundred thousand rand) where they appear in clause 8.1 and the replacement thereof with the words and numbers
R449,689,872.46 (four hundred and forty nine million six hundred and eighty nine thousand and eight hundred and seventy two rand forty six cents);
| | ---- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



| | 3.3. | R4,606,000 (four million six hundred and six thousand rand) where they appear in clause 9.1.1 and the replacement thereof with the words and numbers
R4,496,898.72 (four million four hundred and ninety six thousand and eight hundred and ninety eight rand seventy two cents); and
| | ---- | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



| | 3.4. | R445,994,000 (four hundred and forty five million and nine hundred and ninety four thousand rand) where they appear in clause 9.1.2 and the replacement thereof with the words and
numbers R445,192,974.00 (four hundred and forty five million one hundred and ninety two thousand and nine hundred and seventy four rand).
| | ---- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



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|4. | EXTENSION
|-- | ---------

The Parties hereby extend the date for fulfilment of the Condition Precedent
contained in clause 4.1.14 to 14 June 2013.



|5. | SAVINGS CLAUSE
|-- | --------------

Save to the extent specifically or by necessary implication modified in
or inconsistent with the provisions of this Addendum or unless otherwise agreed in writing between the Parties, all the terms and conditions of the Sale of Business Agreement shall mutatis mutandis continue to apply.



|6. | COSTS
|-- | -----

Each Party will bear and pay its own legal costs and expenses of and incidental
to the negotiation, drafting, preparation and implementation of this Addendum.



|7. | SIGNATURE
|-- | ---------



| | 7.1. | This Addendum is signed by the Parties on the dates and at the places indicated below.
| | ---- | --------------------------------------------------------------------------------------



| | 7.2. | This Addendum may be executed in counterparts, each of which shall be deemed an original, and all of which together shall constitute one and the same Addendum as at the date of signature of the Party last signing one of
the counterparts.
| | ---- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



| | 7.3. | The persons signing this Addendum in a representative capacity warrant their authority to do so.
| | ---- | ------------------------------------------------------------------------------------------------



|    |  |                                    
|--- |  | -----------------------------------
|FOR |  | HARMONY GOLD MINING COMPANY LIMITED



|           |  |                                                      
|---------- |  | -----------------------------------------------------
|Signature: |  | /s/                                                  
|           |  | who warrants that he / she is duly authorised thereto
|Name:      |  | Frank Abbott                                         
|Date:      |  | 24 May 2013                                          
|Place:     |  | Randfontein                                          



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|    |  |                                                          |  | 
|--- |  | -------------------------------------------------------- |  | 
|FOR |  | BUSINESS VENTURE INVESTMENTS NO 1692 PROPRIETARY LIMITED



|           |  |                                                      
|---------- |  | -----------------------------------------------------
|Signature: |  | /s/                                                  
|           |  | who warrants that he / she is duly authorised thereto
|Name:      |  | Frank Abbott                                         
|Date:      |  | 24 May                                               
|Place:     |  | Randfontein                                          



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