<PAGE>
 
                                                                     Exhibit 2.2

                                                                           ATLAS
                                                                  EXECUTION COPY
                                                                            CORP







                           STOCK PURCHASE AGREEMENT

                                BY AND BETWEEN

                               ATLAS CORPORATION

                                      AND

                          ARIMETCO INTERNATIONAL INC.




                          DATED AS OF OCTOBER 7, 1996
<PAGE>
 
                                 TABLE OF CONTENTS
                                 -----------------
<TABLE>
<CAPTION>


<S>                       <C>                                       <C>
ARTICLE I    Purchase and Sale of Shares.............................  2
     Section 1.1  Purchase and Sale..................................  2
     Section 1.2  Purchase Consideration.............................  2
     Section 1.3  Other Deliveries...................................  3

ARTICLE II   Representations and Warranties of Seller................  5
     Section 2.1  Authorization; Binding Obligation..................  5
     Section 2.2  Ownership of the Arisur Shares.....................  5
     Section 2.3  Ownership of the Minera Andacaba Shares............  6
     Section 2.4  Consents and Approvals; No Violations..............  7
     Section 2.5  Arisur and Minera Andacaba Organization............  8
     Section 2.6  Financial Information..............................  8
     Section 2.7  Absence of Undisclosed Liabilities.................  9
     Section 2.8  Absence of Adverse Changes.........................  9
     Section 2.9  Taxes.............................................. 10
     Section 2.10 Title to Properties................................ 10
     Section 2.11 Personal and Real Properties....................... 11
     Section 2.12 Environmental Matters.............................. 12
     Section 2.13 Notes, Accounts Receivable......................... 12
     Section 2.14 Contracts, Etc..................................... 13
     Section 2.15 Employees and Organizational Chart................. 13
     Section 2.16 Litigation......................................... 14
     Section 2.17 Business Permits................................... 14
     Section 2.18 Insurance.......................................... 15
     Section 2.20 Bank Accounts; Powers of Attorney.................. 15
     Section 2.21 Minute Books, etc.................................. 16
     Section 2.22 Disclosure......................................... 16
     Section 2.23 Brokers............................................ 16

ARTICLE III  Representations and Warranties of Buyer................. 17
     Section 3.1  Authorization; Binding Obligation.................. 17
     Section 3.2  No Conflicts....................................... 18
     Section 3.3  Investment; Experience............................. 18
     Section 3.4  Brokers............................................ 18

ARTICLE IV        Covenants.......................................... 19
     Section 4.1  Covenant Not to Compete............................ 19
     Section 4.2  Transfer Taxes..................................... 19
     Section 4.3  Best Efforts....................................... 19
     Section 4.4  Further Assurances................................. 20
</TABLE> 

<PAGE>
 
<TABLE> 
<CAPTION> 

<S>       <C>                                                       <C>  
ARTICLE V  Indemnification and Related Matters...................... 21
     Section 5.1  Indemnification by Seller......................... 21
     Section 5.2  Indemnification by Buyer.......................... 21
     Section 5.3  Procedure......................................... 21
     Section 5.4  Related Matters................................... 23

ARTICLE VI        Miscellaneous..................................... 24
     Section 6.1  Headings.......................................... 24
     Section 6.2  Amendment......................................... 24
     Section 6.3  Notices........................................... 24
     Section 6.4  Successors........................................ 25
     Section 6.5  Entire Agreement.................................. 26
     Section 6.6  Severability...................................... 26
     Section 6.7  Third Parties..................................... 26
     Section 6.8  Counterparts...................................... 26
     Section 6.9  Governing Law..................................... 26
</TABLE>

SCHEDULES

Schedule 2.7      Disclosed Liabilities
Schedule 2.8      Certain Adverse Changes
Schedule 2.9      Taxes
Schedule 2.10     Title to Properties
Schedule 2.11(i)  Personal Properties
Schedule 2.11(ii) Real Properties
Schedule 2.14     Contracts, Etc.
Schedule 2.15     Employees and Organizational Chart
Schedule 2.17     Business Permits
Schedule 2.18     Insurance
Schedule 2.20     Bank Accounts; Powers of Attorney
Schedule 4.1      Permitted Competition


EXHIBITS

Exhibit A         Note
Exhibit B         Report of Verna & Associates
<PAGE>
 
                           STOCK PURCHASE AGREEMENT
                           ------------------------


          This STOCK PURCHASE AGREEMENT ("Agreement") is made as of the seventh
day of October, 1996, by and between Atlas Corporation, a Delaware corporation
("Buyer") and Arimetco International Inc., Canadian corporation ("Seller").

                             W I T N E S S E T H:
                             ------------------- 

          WHEREAS, Seller is the record and beneficial owner of 500 ordinary
shares, nominal value US$1.00 per share of Arisur, Inc. a Cayman Islands company
("Arisur"), constituting fifty percent (50%) of the issued and outstanding
shares of Arisur (the "Arisur Shares"); and

          WHEREAS, Seller is also the record and beneficial owner of 88 ordinary
shares, nominal value 1 Boliviano per share, of Compania Minera Andacaba S.A., a
Bolivian corporation ("Minera Andacaba"), constituting one percent (1%) of the
issued and outstanding shares of Minera Andacaba (the "Minera Andacaba Shares");
and

          WHEREAS, pursuant to an agreement of even date herewith, Buyer is
purchasing all of the issued and outstanding shares of Suramco Metals, Inc., a
Nevada corporation ("Suramco"), which is the record and beneficial owner of the
remaining fifty percent (50%) of the issued and outstanding shares of Arisur;
and

          WHEREAS, Arisur and Suramco, respectively, are the record and
beneficial owners of 4,488 and 4,224 ordinary shares, nominal value 1 Boliviano
per share, of Minera Andacaba,
<PAGE>
 
constituting, respectively, fifty-one percent (51%) and forty-eight percent
(48%) of the issued and outstanding shares of Minera Andacaba; and

          WHEREAS, pursuant to this Agreement, Seller desires to sell and
transfer the Arisur Shares and the Minera Andacaba Shares to Buyer and Buyer
desires to purchase and acquire the Arisur Shares and the Minera Andacaba Shares
from Seller, all upon the terms hereinafter set forth.

          NOW, THEREFORE, it is agreed as follows:



                                   ARTICLE I

                          Purchase and Sale of Shares
                          ---------------------------

          Section 1.1  Purchase and Sale. On the terms set forth herein, Buyer
hereby purchases from Seller, and Seller hereby sells, transfers and delivers to
Buyer, all right, title and interest in, free of all Liens (as hereinafter
defined), (i) the Arisur Shares (which are hereby deemed released from the
pledge dated August 1, 1996 in favor of Buyer) and (ii) the Minera Andacaba
Shares, for the purchase consideration set forth in Section 1.2 hereof.

          Section 1.2  Purchase Consideration. The purchase consideration (the
"Purchase Consideration") for the Arisur Shares and the Minera Andacaba Shares
shall consist of the sum of the following:

          (a)  Buyer hereby confirms receipt of all accrued and unpaid interest
               due and payable under that certain Loan Agreement, dated as of
               August 1, 1996, by and between Buyer and Seller, and hereby
               releases and discharges Seller from its obligation to repay Buyer
               the aggregate principal amount of US$1,800,000 under such Loan

                                       2
<PAGE>
 
          Agreement, and further releases all security and guaranties supporting
          such principal amount;

     (b)  Buyer has hereby paid to Seller US$300,000, receipt of which by Seller
          is hereby acknowledged; and

     (c)  On October 31, 1996, (i) Seller shall cancel and return to Buyer the
          note referred to in Section 1.3(f) below and (ii) Buyer shall pay to
          Seller the US$900,000 principal amount of such note in immediately
          available funds by wire transfer to a bank account specified by
          Seller.

     Section 1.3  Other Deliveries. Simultaneously with the transfer of the
Arisur Shares and the Minera Andacaba Shares, the parties acknowledge that the
following actions have been taken:

     (a)  Resignations. All members of the Board of Directors of Arisur and all
          officers of Arisur have delivered their resignations dated the date
          hereof;

     (b)  Board Resolutions. Seller has delivered to Buyer a certificate of the
          Secretary of Seller certifying the resolutions of the Board of
          Directors of Seller approving the execution and performance of this
          Agreement and the transactions contemplated hereby;
     
     (c)  Good Standing. Seller has delivered to Buyer a certificate of good
          standing (or, in the case of Minera Andacaba, a copy of its
          certificate of incorporation and by-laws, together with all amendments
          thereto, registered with the appropriate Registry of Commerce) in
          respect of Arisur, including a copy of its articles of

                                       3
<PAGE>
 
          incorporation certified by a notary public in the Cayman Islands as
          being a true and correct copy thereof;

     (d)  Title and Geological Data. Seller has delivered, or caused to be
          delivered, to Buyer copies of all title, geological, geochemical,
          geophysical and engineering data in the possession of Seller, Arisur
          or Minera Andacaba or under their control, in respect of all
          properties owned, controlled or evaluated by Arisur (including any
          branch thereof) and Minera Andacaba;

     (e)  Share Certificates and Stock Transfers. Seller has delivered to Buyer
          the certificates representing the Arisur Shares and the Minera
          Andacaba Shares, in each case together with stock transfers duly and
          validly endorsed for transfer on behalf of Seller; and

     (f)  Note. Buyer has delivered to Seller a note, in the form annexed as
          Exhibit A hereto, representing the obligation of Buyer to pay on
          October 31, 1996 Seller (without interest thereon other than in the
          case of default, in which case the rate shall be the rate stipulated
          for defaults under that certain Loan Agreement, dated as of August 1,
          1996, by and between Buyer and Seller), the amount referred to in
          Section 1.2(c) above.

                                       4
<PAGE>
 
                                  ARTICLE II

                   Representations and Warranties of Seller
                   ----------------------------------------

     Seller represents and warrants to Buyer as follows (all representations and
warranties with respect to Arisur being deemed to apply with equal force to each
branch of Arisur established in Bolivia or elsewhere):

     Section 2.1  Authorization; Binding Obligation. Seller is a company duly
organized, validly existing and in good standing under the laws of Canada; it
has all requisite corporate power and authority to own, operate and lease the
properties and assets it now owns, operates and leases and to carry on its
businesses as presently (or as contemplated to be) conducted; it has the
requisite power and authority to execute, deliver and perform this Agreement and
any agreements contemplated herein to which it is or will be party and to
consummate the transactions contemplated hereby and thereby; all action on its
part necessary to approve or to authorize the execution, delivery and
performance of this Agreement and any such documents to which it is party and
the consummation of the transactions contemplated hereby and thereby has been
duly taken; and this Agreement is the valid and binding obligation of,
enforceable in accordance with its terms against, it, except as enforcement
thereof may be limited by bankruptcy, insolvency, conservatorship, receivership,
liquidation, reorganization, moratorium or similar laws or general equitable
principles.

     Section 2.2  Ownership of the Arisur Shares. The Arisur Shares constitute
fifty percent (50%) the issued and outstanding share capital of Arisur; Seller
is the sole record and beneficial owner of the Arisur Shares, free and clear of
all liens, mortgages, charges, security interests, defects in title, adverse
claims, encumbrances, conflicting claims to ownership, any options,

                                       5
<PAGE>
 
rights of first refusal or similar rights, or any restrictions or limitations
on, or conflicting claims with respect to, the use, voting, transfer, receipt of
income or other exercise of any attributes of ownership (collectively, "Liens");
as a result of the transfer of the Arisur Shares pursuant to this Agreement,
Buyer has acquired good and marketable title to the Arisur Shares free and clear
of all Liens; other than this Agreement, there are no agreements arrangements or
understandings relating to issuance, ownership, transfer or other rights with
respect to the Arisur Shares; the Arisur Shares are duly and validly issued and
outstanding, fully paid and non-assessable and have not been issued in violation
of any preemptive or similar rights of stockholders; and there is no option,
warrant, subscription, or other agreement to issue any security or other
instrument convertible into or exchangeable for, or any other right, commitment,
understanding or arrangement calling for the issuance of any additional shares
of capital stock by Arisur. Arisur does not own any shares or other equity in
any other corporation or entity other than Minera Andacaba.

     Section 2.3  Ownership of the Minera Andacaba Shares. The Minera Andacaba
Shares constitute one percent (1%) the issued and outstanding share capital of
Minera Andacaba; Seller is the sole record and beneficial owner of the Minera
Andacaba Shares, free and clear of all Liens; as a result of the transfer of the
Minera Andacaba Shares pursuant to this Agreement, Buyer has acquired good and
marketable title to the Minera Andacaba Shares free and clear of all Liens;
other than this Agreement, there are no agreements arrangements or
understandings relating to issuance, ownership, transfer or other rights with
respect to the Minera Andacaba Shares; the Minera Andacaba Shares are duly and
validly issued and outstanding, fully paid and non-assessable and have not been
issued in violation of any preemptive or similar rights of

                                       6
<PAGE>
 
stockholders; and there is no option, warrant, subscription, or other agreement
to issue, or any security or other instrument convertible into or exchangeable
for, or any other right, commitment, understanding or arrangement calling for
the issuance of, any additional shares of capital stock by Minera Andacaba.
Minera Andacaba does not own any shares or other equity in any other corporation
or entity.

     Section 2.4  Consents and Approvals; No Violations. The execution and
delivery of this Agreement and any agreement contemplated herein and the
consummation of the transactions contemplated hereby and thereby will not:
violate or conflict with any provision of the respective certificates of
incorporation, by-laws or other constitutional documents of Seller, Arisur or
Minera Andacaba; breach, violate or constitute an event of default (or an event
which with the lapse of time or the giving of notice or both would constitute an
event of default) under, give rise to any right of termination, cancellation,
modification or acceleration under, or require any consent or the giving of any
notice under, any note, bond, indenture, mortgage, security agreement, lease,
license, franchise, permit, agreement or other instrument or obligation to which
Seller, Arisur or Minera Andacaba is a party, or by which Seller, Arisur or
Minera Andacaba or any of their respective properties or assets may be bound, or
result in the creation of any Lien or other right of any third party of any kind
whatsoever upon such properties or assets pursuant to the terms of any such
instrument or obligation; violate or conflict with any law, statute, ordinance,
code, rule, regulation, judgment, order, writ, injunction, decree or other
instrument applicable to Seller, Arisur or Minera Andacaba or by which their
respective properties or assets may be bound or require, on the part of said
entities, any filing with, or

                                       7
<PAGE>
 
permit, license, exemption, consent, authorization or approval of, or the giving
of any notice to, any governmental or regulatory agency other than such as has
been obtained.

     Section 2.5  Arisur and Minera Andacaba Organization. Arisur and Minera
Andacaba are companies duly organized, validly existing and in good standing
under the laws of the Cayman Islands and Bolivia, respectively, have all
requisite power and authority to own, lease and operate the properties currently
(or contemplated to be) owned, leased or operated by Arisur and Minera Andacaba
(as the case may be) and to conduct their respective businesses as presently (or
contemplated to be) conducted.

     Section 2.6  Financial Information. Seller has delivered to Buyer on or
prior to the date of this Agreement (i) the audited consolidated balance sheets
of each of Arisur and Minera Andacaba as at September 30, 1995, 1994 and 1993
and their respective audited statements of income and cash flow for the fiscal
years then ended, including the notes thereto (collectively, the "Financial
Statements"), in each case accompanied by the qualified report of Verna &
Associates in the form attached as Exhibit B hereto, and (ii) the unaudited
balance sheets of Arisur and Minera Andacaba as at June 30, 1996 and the related
unaudited statements of operations for the nine months then ended (the "Interim
Financial Statements"). The Financial Statements and the Interim Financial
Statements (x) have been prepared from the books and records of Arisur and
Minera Andacaba, (y) have been prepared in accordance with generally accepted
accounting principles consistently applied during such periods and (z) present
fairly the respective financial conditions, results of operations and cash flows
of Arisur and Minera Andacaba as at the dates, and for the periods, stated
therein, subject, in the case of the Interim Financial Statements, to normal and
customary year-end adjustments.

                                       8
<PAGE>
 
     Section 2.7  Absence of Undisclosed Liabilities. Neither Arisur nor Minera
Andacaba has any liabilities or obligations of any nature, whether accrued,
absolute, contingent or otherwise, except (i) as set forth in Schedule 2.7 and
as set forth or reserved against in the Interim Financial Statements, (ii)
liabilities or obligations incurred since June 30, 1996 in the ordinary course
of business and consistent with past practice and which individually and in the
aggregate are not material to Arisur or Minera Andacaba.

     Section 2.8  Absence of Adverse Changes. Since September 30, 1995, Arisur
and Minera Andacaba have carried on their respective businesses in the ordinary
course and consistent with past practice. Except as set forth in Schedule 2.8
hereto, since September 30, 1995 there has not been: (i) any material adverse
change in the respective conditions (financial or otherwise), assets,
liabilities, operations, businesses or prospects of Arisur or Minera Andacaba;
(ii) any material damage, destruction or loss, whether or not covered by
insurance, adversely affecting the respective assets or operations of Arisur or
Minera Andacaba; (iii) any sale, transfer, lease or other disposition of any of
the respective material properties or assets of Arisur or Minera Andacaba, other
than sales from inventory in the ordinary course of business; (iv) any increase
in the compensation payable or to become payable by Arisur or Minera Andacaba to
any of their respective officers, or any increase in such compensation payable
or to become payable to employees or agents, or any bonus payment or arrangement
made to, or to be made to or with, any thereof; (v) any labor trouble or any
event or condition of any character materially and adversely affecting the
operations, prospects or businesses of Arisur or Minera Andacaba; (vi) any
discharge or satisfaction of any Lien, or payment of any obligation or
liability, absolute, accrued, contingent or otherwise, whether due or to become
due, other

                                       9
<PAGE>
 
than current liabilities shown on the Interim Financial Statements; (vii) any
Lien imposed on any of the respective properties or assets, tangible or
intangible, of Arisur or Minera Andacaba; or (viii) paid or declared any
dividend or distribution in respect of shares of the respective capital stocks
of Arisur and Minera Andacaba or any repurchase or agreement to repurchase any
such shares.

     Section 2.9  Taxes. Except as set forth in Schedule 2.9 hereto, Arisur and
Minera Andacaba have duly filed all tax returns required to be filed and have
paid in full all taxes, interest, penalties, assessments and deficiencies due or
claimed to be due from all taxing authorities having jurisdiction over Arisur
and Minera Andacaba (including taxes on properties, income, franchises,
licenses, sales, payrolls and social security). The provisions for income and
other taxes payable reflected in the respective consolidated balance sheets of
Arisur and Minera Andacaba as of the respective Financial Statements and in the
Interim Financial Statements make adequate provision for all accrued and unpaid
taxes of Arisur and Minera Andacaba as at said dates, whether or not disputed,
and Arisur and Minera Andacaba have made adequate provision for such taxes on
their respective books and records. There are no tax liens (other than liens for
taxes which are not yet due and payable) on any of the respective properties of
Arisur or Minera Andacaba, no tax claims asserted, no basis for any such claim
and no agreements with or received from any governmental or regulatory agency
pertaining to the tax treatment of Arisur or Minera Andacaba or any of their
interests in any of their respective properties.

     Section 2.10  Title to Properties. All of the property and assets of every
kind and description which are reflected on the consolidated balance sheets of
Arisur and Minera Andacaba as at June 30, 1996 (other than inventory transferred
by Arisur or Minera Andacaba

                                      10
<PAGE>
 
in the ordinary course of business), is either (i) owned absolutely by Arisur or
Minera Andacaba, as the case may be, free and clear of Liens, except as set
forth in Schedule 2.10 hereto, or (ii) leased or otherwise used or exploited
under concessions or similar rights by Arisur or Minera Andacaba, pursuant to
leases, concessions or similar rights listed in Schedule 2.10 hereto. All
leases, concessions or rights set forth in Schedule 2.10 are valid, binding and
in full force and effect. Neither Arisur or Minera Andacaba nor, to the best
knowledge of Seller, any other party thereto, is in default thereunder, and no
event has occurred which, with notice and/or lapse of time, would constitute a
default by Arisur or Minera Andacaba, or to the best knowledge of Seller, any
other party thereto. Arisur and Minera Andacaba have all easements and rights,
including easements for power lines, water lines, roadways and other access,
necessary to conduct their respective businesses as currently conducted.

     Section 2.11  Personal and Real Properties. (i) Schedule 2.11(i) hereto
correctly sets forth an accurate list of all tangible personal property which
was owned of record or beneficially by Arisur and Minera Andacaba as at
September 30, 1996, together with any material changes since such date,
including, without limitation, all vehicles (motor or other) and all machinery
and equipment; all such vehicles, machinery and equipment and other personal
property are in good operating condition and repair, reasonable wear and tear
excepted, and, to the best of Seller's knowledge after reasonable inquiry, the
operation thereof conforms with all applicable regulations and other laws. All
such personal property is owned by Arisur or Minera Andacaba, as the case may
be, free and clear of any Lien, except as set forth in Schedule 2.11(i) hereto.

     (ii) Schedule 2.11(ii) hereto correctly sets forth an accurate list and
summary description of all real property which was owned of record or
beneficially by Arisur and Minera

                                      11
<PAGE>
 
Andacaba as of the date hereof; all installations, sites and places of business
located thereon are, in all material respects, in good operating condition and
repair, reasonable wear and tear excepted, and, to the knowledge of Seller after
reasonable inquiry, conform with all applicable ordinances and existing and
proposed regulations and building, zoning and other laws.

     Section 2.12 Environmental Matters: There are no conditions, occurrences or
activities at or on any of the properties described in Schedule 2.11(ii) hereto,
or any other real property in which either Arisur or Minera Andacaba holds any
interest, which constitute a violation of, or give rise to liability under, any
applicable laws, regulations, ordinances or orders providing for health and
safety or protection of the environment, or that may give rise to an obligation
to contribute to the remediation of any contamination of air, water or land
(collectively, "Environmental Laws"). Such properties have not in the past, and
to the knowledge of Seller after due inquiry as of the date hereof, are not now
subject to any investigation, assessment, or study by any person or governmental
or regulatory agency related to potential or actual violation or enforcement of
any Environmental Law. Arisur and Minera Andacaba are in compliance with all
notification and reporting requirements of any Environmental Laws applicable to
their respective operations and properties.

     Section 2.13 Notes, Accounts Receivable. All receivables of Arisur and
Minera Andacaba (including accounts receivable, loans receivable, notes and
advances) have arisen from bona fide transactions in the ordinary course of
business and consistent with past practice; are owned by Arisur and Minera
Andacaba free and clear of any Liens and are accurately reflected on the Interim
Financial Statements or with respect to receivables created after June 30, 1996,
are accurately and fairly reflected in the books and records of Arisur and
Minera Andacaba and,

                                      12
<PAGE>
 
except for any reserve set forth in the Interim Financial Statements (or with
respect to receivables created after June 30, 1996 in the books and records of
Arisur and Minera Andacaba), are fully collectible.

     Section 2.14 Contracts, Etc. Schedule 2.14 hereto correctly sets forth all
agreements, arrangements or understandings, whether written or oral, in respect
of any indebtedness between Arisur or Minera Andacaba and any of their
respective Affiliates (as such term is defined in Rule 405 of the Securities Act
of 1933, as amended (the "Securities Act")) and all such indebtedness has been
paid in full or otherwise cancelled and all such arrangements, understandings or
agreements have been terminated as of the date hereof. All material contracts
and commitments of Arisur and Minera Andacaba, as of the date hereof, are valid
and in full force and effect. Neither Arisur nor Minera Andacaba nor, to the
best knowledge of Seller, any other party thereto, is in default thereunder, and
no event has occurred which, with notice and/or lapse of time, would constitute
a default by Arisur or Minera Andacaba, or to the best knowledge of Seller, any
other party thereto. Schedule 2.14 hereto lists (except to the extent listed in
other schedules to this Agreement) all such contracts and commitments as of June
30, 1996, and there have been no material changes thereto since such date.

     Section 2.15 Employees and Organizational Chart. Schedule 2.15 hereto
contains a true and complete list as of June 30, 1996 of (i) all of the
employees of Arisur and Minera Andacaba, whether full-time or part-time and
consultants engaged by such entities and the compensation or other benefits
payable to each, together with an organizational chart, as of such date,
indicating names, titles and responsibilities of their respective management and
supervisory personnel, and (ii) all employment or collective bargaining or
consulting agreements in respect

                                      13
<PAGE>
 
of employees of Arisur and Minera Andacaba, and there has been no material
change in the information set forth in such Schedule through the date of this
Agreement. There are no disputes currently subject to any grievance procedure,
arbitration or litigation, and neither Arisur or Minera Andacaba, nor, to the
best knowledge of Seller, any other party thereto, is in default thereunder, and
no event has occurred which with notice and/or lapse of time, would constitute a
default by Seller, or, to the best knowledge of Seller, any other party thereto.
There are no strikes, lockouts, work stoppages, slowdowns, jurisdictional
disputes occurring or, to Seller's knowledge after due inquiry, threatened in
connection with the properties or operations of Arisur or Minera Andacaba.

     Section 2.16 Litigation. There is no Litigation (as hereinafter defined)
(i) by or before any court, governmental body or other regulatory or
administrative agency or commission, domestic or foreign, or any arbitration
pending, or, to the knowledge of Seller after due inquiry, threatened, to which
Seller, Arisur or Minera Andacaba is a party or by which any of their respective
assets or properties may be bound or affected, which, if adversely decided would
have a material adverse effect on Arisur or Minera Andacaba; and (ii) by or
before any court, governmental agency, or arbitrator, in each case pending or,
to the knowledge of Seller after due inquiry, threatened, which seeks to
restrain, enjoin, prevent the consummation of, or otherwise challenge this
Agreement or any of the transactions contemplated hereby. For purposes of this
Agreement, "Litigation" shall mean any action, suit, claim, proceeding,
investigation or written governmental inquiry.

     Section 2.17 Business Permits. Arisur and Minera Andacaba have, to the best
of Seller's knowledge after due inquiry, secured all permits, licenses or other
authorizations necessary from

                                      14
<PAGE>
 
all relevant governmental or regulatory agencies to operate their respective
businesses as presently conducted or as presently proposed to be conducted.  All
such permits, licenses or other authorizations are listed in Schedule 2.17
hereto.  Seller shall cooperate with Buyer (at no cost to Buyer) to obtain any
additional, or to modify any existing, permits or authorizations necessary in
connection with the transactions contemplated hereby.

     Section 2.18 Insurance.  Arisur and Minera Andacaba are adequately insured
with reputable insurers in respect of their respective businesses, operations
and the properties and assets related thereto, against risk normally insured
against by companies in similar lines of business. Schedule 2.18 hereto lists
all fire, theft, casualty, liability, business disruption, products liability
and other insurance policies insuring such businesses, operations, properties
and assets, specifying with respect to each such policy the name of the insurer,
the risk insured against, the limits of coverage, the deductible amount (if
any), the premium rate and the date through which coverage will continue by
virtue of premiums already paid.

     Section 2.19 Compliance with Applicable Law.  Arisur and Minera Andacaba
have, to the knowledge of Seller after due inquiry, complied with all applicable
laws and regulations of domestic and foreign governments and all agencies
thereof which affect the respective businesses of Arisur and Minera Andacaba or
any owned, used or leased properties employed in such businesses and to which
said entities may be subject, including, without limitation, safety, health and
environmental laws and regulations, and no claims have been filed against Arisur
or Minera Andacaba alleging a violation of any such laws or regulations.

     Section 2.20 Bank Accounts; Powers of Attorney.  Schedule 2.20 hereto sets
forth a complete and correct list of showing (i) all bank accounts of Arisur and
Minera Andacaba,

                                       15
<PAGE>
 
together with, in respect of each such account, the account number, the names of
all signatories thereof and the authorized powers of each such signatory; and
(ii) the names of all persons holding powers of attorney from Arisur and Minera
Andacaba and a summary statement of the terms thereof.

     Section 2.21 Minute Books, etc.  The respective minute books, stock
certificates and stock ledgers of Arisur and Minera Andacaba have been delivered
to Buyer and are complete and correct in all material respects and fairly
reflect the conduct of the respective businesses of Arisur and Minera Andacaba.
The minute books of Arisur and Minera Andacaba contain accurate and complete
records of all meetings or written consents to action of their respective Boards
of Directors and stockholders and accurately reflect all corporate actions of
Arisur and Minera Andacaba which are required by law to be passed upon by such
Boards of Directors or stockholders.

     Section 2.22 Disclosure.  No representation or warranty by Seller contained
in this Agreement and no statement contained in any Schedule, certificate or
other document or instrument delivered or to be delivered by Seller pursuant to
this Agreement contains or will contain any untrue statement of a material fact
or omits or will omit to state any material fact necessary to make the
statements contained therein not misleading.  For the avoidance of confusion, it
is hereby stipulated that with respect to any oral agreement or commitment
disclosed in any Schedule, only those terms of such oral agreement expressly set
forth in such Schedule shall be deemed to have been disclosed.

     Section 2.23 Brokers.  No broker or finder has acted on behalf of Seller in
connection with this Agreement or any transactions provided for hereby and
Seller agrees to indemnify
                                       16
<PAGE>
 
Buyer for any broker's or finder's fees that may be payable in connection with
any action taken by Seller.

                                  ARTICLE III

                    Representations and Warranties of Buyer
                    ---------------------------------------

          Buyer represents and warrants to Seller as follows:

     Section 3.1  Authorization; Binding Obligation.  Buyer is a company duly
organized, validly existing and in good standing under the laws of the State of
Delaware; it has all requisite corporate power and authority to own, operate and
lease the properties and assets it now owns, operates and leases and to carry on
its business as presently (or as contemplated to be) conducted; it has the
requisite power to execute, deliver and perform this Agreement and any documents
contemplated herein to which it is or will be a party and to consummate the
transactions contemplated hereby and thereby; all action on its part necessary
to approve or to authorize the execution, delivery and performance of this
Agreement and any such documents to which it is party and the consummation of
the transactions contemplated hereby and thereby has been duly taken; this
Agreement is the valid and binding obligation of, enforceable in accordance with
its terms against, Buyer, except as enforcement thereof may be limited by
bankruptcy, insolvency, conservatorship, receivership, liquidation,
reorganization, moratorium or similar laws or general equitable principles; and
any related document thereto is, or upon execution and delivery thereof will be,
a valid and binding obligation of, enforceable in accordance with its terms
against, it, except as enforcement thereof may be limited by

                                       17
<PAGE>
 
bankruptcy, insolvency, conservatorship, receivership, liquidation,
reorganization, moratorium or similar laws or general equitable principles.

     Section 3.2  No Conflicts.  Neither the execution, delivery or performance
by Buyer of this Agreement and any agreement contemplated herein, nor the
consummation by it of the transactions contemplated hereby or thereby, will: (a)
constitute an event of default under, permit the termination of, give rise to a
right to accelerate any indebtedness under any contract, lease, or governmental
permit to which Buyer is a party, is maker or guarantor, or by which it is
bound; (b) violate any order, writ, injunction, decree, judgment, ruling or law
applicable to Buyer or by which Buyer or any of its properties is bound; or (c)
require any consent, approval or authorization of any governmental or regulatory
agency; other than for such of the foregoing matters which, or the absence of
which, would not, individually or when taken together with all other such
related matters, have a material adverse effect on Buyer.

     Section 3.2  Investment; Experience.  Buyer is purchasing the Arisur Shares
and the Minera Andacaba Shares for investment only and not with a view to resale
or distribution thereof. Buyer is experienced in the acquisition and management
of businesses similar to those of Arisur and Minera Andacaba.

     Section 3.3 Brokers.  No broker or finder has been employed which is
entitled to a fee by reason of the transactions contemplated hereby other than
Endeavour Financial Inc., whose fees shall be borne in their entity by Buyer.

                                       18
<PAGE>
 

                                  ARTICLE IV

                                   Covenants
                                   ---------

     Section 4.1  Covenant Not to Compete.  Except as specifically contemplated
and referred to in Schedule 4.1 hereto or that certain consulting agreement of
even date herewith between Buyer and Suramco Holdings, Inc., each of Seller and
each affiliate of Seller (as such term is defined in Rule 405 of the Securities
Act) agrees that, for a period of three (3) years after the date of this
Agreement, Seller and each such affiliate of Seller shall not, directly or
indirectly, own (other than not more than 2% of the issued and outstanding
capital stock of any company whose shares are traded on a national stock
exchange or quoted on NASDAQ in the United States or which are traded on the
facilities of a Designated Offshore Securities Market (as defined in Rule 902
under the Securities Act)), manage, operate, work for, consult with or otherwise
provide services to, or otherwise be affiliated with, any corporation, person or
entity engaged in the mining and/or milling or other processing of base or
precious metals in Bolivia.

     Section 4.2  Transfer Taxes.  Seller shall be responsible for, and agrees
to pay promptly when and if due, all transfer, stamp, use or any other similar
taxes payable in any jurisdiction in connection with or arising from the sale
and transfer of the Arisur Shares and the Minera Andacaba Shares to Buyer
hereunder.

     Section 4.3  Best Efforts.
                  
     (a)  Upon the terms hereof, each of the parties hereto agrees to take or
cause to be taken, all action and to do, or cause to be done, all things
necessary, proper or advisable to consummate and make effective the transactions
contemplated by this Agreement and any related documents thereto.

                                       19
<PAGE>
 
     (b)  Except as otherwise expressly provided for in this Agreement, Buyer
and Seller shall use their best efforts to obtain at the earliest practicable
date all consents required for the consummation of the transactions contemplated
by this Agreement and any related documents thereto, including without
limitation, all consents, permissions and approvals required by the relevant
authorities in the Cayman Islands and Bolivia.

     (c)  Buyer and Seller shall provide such information and cooperate fully
with each other in making such applications, filings and other submissions which
may be required or reasonably necessary in order to obtain all approvals,
consents, authorizations and waivers as may be required from any governmental or
regulatory agency and others in connection with the transactions contemplated by
this Agreement and any documents related thereto.

     (d)  Except as otherwise expressly provided for in this Agreement, Buyer
and Seller shall promptly take all actions necessary to make each filing,
including without limitation, any supplemental filing, which either of them may
be required to make with any governmental or regulatory agency as a condition to
or consequence of the consummation of the transactions contemplated by this
Agreement or any document related thereto.

     Section 4.4  Further Assurances.  Subject to the terms and conditions of
this Agreement, each of the parties hereto agrees to use all reasonable efforts
to take, or cause to be taken, all action and to do, or cause to be done, all
things necessary, proper or advisable under applicable laws and regulations to
consummate and make effective the transactions contemplated by this Agreement.
In case at any time after the date of this Agreement any further action is
necessary or desirable to carry out the purposes hereof, the proper officers of
Buyer, Seller, Arisur and Minera Andacaba shall take all such action.

                                       20
<PAGE>
 
                                   ARTICLE V
                      Indemnification and Related Matters
                      -----------------------------------

     Section 5.1  Indemnification by Seller.  Seller agrees to indemnify and
hold harmless Buyer and its directors, officers and employees against and in
respect of any and all loss, liability, obligation, damage, deficiency or
expense resulting from (a) any misrepresentation, breach of any warranty or non-
fulfillment of any agreement of Seller under the terms of this Agreement or in
any agreement or certification furnished pursuant hereto and (b) any actions,
suits, proceedings, demands, judgments, costs and reasonable legal,
investigatory and other expenses incident to any of the foregoing (regardless of
whether, in the case of third party actions, suits or proceedings, Seller may
have a meritorious defense).

     Section 5.2  Indemnification by Buyer.  Buyer agrees to indemnify and hold
harmless Seller and its directors, officers and employees against and in respect
of any and all loss, liability, obligation, damage, deficiency or expense
resulting from (a) any misrepresentation, breach of any warranty or non-
fulfillment of any agreement of Buyer under the terms of this Agreement or in
any statement or certification furnished pursuant hereto; and (b) any actions,
suits, proceedings, demands, judgments, costs and reasonable legal,
investigatory and other expenses incident to any of the foregoing (regardless of
whether, in the case of third party actions, suits or proceedings, Buyer may
have a meritorious defense).

     Section 5.3  Procedure.  Promptly after receipt by any person that is
entitled to indemnification under this Section 5 (the "Indemnified Party") of
notice of the commencement of any action in respect of which the Indemnified
Party will seek indemnification hereunder, the Indemnified Party shall notify
the person obligated to provide such indemnification (the

                                       21
<PAGE>
 
"Indemnifying Party") thereof in writing, but any failure to so notify the
Indemnifying Party shall not relieve the Indemnifying Party from any liability
that it may have to the Indemnified Party under this Section 5, except to the
extent that the Indemnifying Party is prejudiced by the failure to give such
notice.  The Indemnifying Party shall be entitled to participate in the defense
of such action and to assume control of such defense with counsel reasonably
satisfactory to such Indemnified Party; provided, however, that:

          (a)  the Indemnified Party shall be entitled to participate in the
     defense of such claim and to employ counsel at its own expense to assist in
     the handling of such claim;

          (b)  the Indemnifying Party shall obtain the prior written approval of
     the Indemnified Party before entering into any settlement of such claim or
     ceasing to defend against such claim, if pursuant to or as a result of such
     settlement or cessation, injunctive or other equitable relief would be
     imposed against the Indemnified Party or the Indemnified Party would be
     adversely affected thereby;

          (c)  the Indemnifying Party shall not consent to the entry of any
     judgment or enter into any settlement that does not include as an
     unconditional term thereof the giving by each claimant or plaintiff to the
     Indemnified Party of a release from all liability in respect of such claim;
     and

          (d)  the Indemnifying Party shall not be entitled to control the
     defense of any claim unless within 15 days after receipt of such written
     notice from the Indemnified Party the Indemnifying Party confirms in
     writing its responsibility for such defense and reasonably demonstrates
     that it will be able to pay the full amount of the reasonably expected
     liability in connection with any such claim.

                                       22
<PAGE>
 
After written notice by the Indemnifying Party to the Indemnified Party of its
election to assume control of the defense of any such action in accordance with
the foregoing, (i) the Indemnifying Party shall not be liable to such
Indemnified Party hereunder for any expenses subsequently incurred by such
Indemnified Party in connection with the defense thereof, and (ii) as long as
the Indemnifying Party is reasonably contesting such action in good faith, the
Indemnified Party shall not admit any liability with respect to, or settle,
compromise or discharge the claim underlying such action without the
Indemnifying Party's prior written consent.  If the Indemnifying Party elects to
so participate in or assume the defense of any such action, the Indemnified
Party shall cooperate with the Indemnifying Party in connection with the
defense.  If the Indemnifying Party does not assume control of the defense of
such claim as provided in this Section 5, the Indemnified Party shall have the
right to defend and/or settle such claim in such manner as it may deem
appropriate at the cost and expense of the Indemnifying Party, and the
Indemnifying Party will promptly reimburse the Indemnified Party therefor in
accordance with this Section 5.  The reimbursement of fees, costs and expenses
required by this Section 5 shall be made by periodic payments during the course
of the investigation or defense, as and when bills are received or expenses
incurred.

     Section 5.4  Related Matters.  (a) Without prejudice to any remedies
available to it by law or otherwise, Buyer shall have the right to offset
against any payments or other consideration payable by it to Seller after the
date of this Agreement pursuant to the terms hereof any claims that Buyer may
have against Seller for any breach of any representations, warranties or
undertakings.

                                       23
<PAGE>
 
     (b) In the event that an Indemnifying Party shall be obligated to
indemnify the Indemnified Party pursuant to this Section 5, an Indemnifying
Party shall, upon payment of such indemnity in full, be subrogated to all rights
of the Indemnified Party with respect to the claims to which such
indemnification relates.  In the event that an Indemnified Party becomes 
entitled to any indemnification from an Indemnifying Party, such indemnification
shall be made in cash upon demand.  Seller shall not be entitled to any
contribution or reimbursement from Arisur or Minera Andacaba with respect to
payments made by Seller under this Section 5.


                                  ARTICLE VI
                                 Miscellaneous
                                 -------------

     Section 6.1  Headings.  The descriptive headings of the several Articles
and Sections of this Agreement are inserted for convenience only and do not
constitute a part of this Agreement.

     Section 6.2  Amendment.  No modification or amendment of this Agreement
shall be effective for any purpose unless in writing and signed by the parties
hereto.

     Section 6.3  Notices.  Any notices other communications required or
permitted hereunder shall be given in writing and shall be delivered or sent by
facsimile, next day delivery service, personal delivery or certified or
registered mail, postage prepaid, addressed as follows:

                          If to Buyer, to:
 
                                       Atlas Corporation
                                       370 17th Street
                                       Suite 3050
                                       Denver, Colorado 80202
                                       Attn:  President
                                       Fax: (303) 629-2445



                                       24
<PAGE>
 
                          Copy to:
                                        
                                          Coudert Brothers
                                          1114 Avenue of the Americas
                                          New York,  New York  10036
                                          Attn:  Jeffrey E. Cohen, Esq.
                                          Fax:  (212) 626-4120


                          If to Seller, to:

                                          Arimetco International, Inc.
                                          335 North Wilmot Road, Suite 410
                                          Tucson, AZ  85711
                                          Attn:  Roy Shipes
                                          Fax: (520) 748-2626

                          Copy to:
                                           Cassels Brock & Blackwell
                                           Scotia Plaza, Suite 2100
                                           40 King Street West
                                           Toronto, Canada  M5H 3C2
                                           Attn:  Lori A. McBurney, Esq.
                                           Fax:  (416) 360-8877


or to such other address or telefax number as shall be furnished in writing by
such party, and any such notice or communication shall be effective and be
deemed to have been given as of the date so dispatched, delivered or mailed;
provided, that, any notice or communications changing any of the addresses set
forth above shall be effective and deemed giving only upon its receipt.

     Section 6.4  Successors.  This Agreement and all of the provisions hereof
shall be binding upon and inure to the benefit of the parties hereto and their
respective successors and permitted assigns, but neither this Agreement nor any
of the rights, interests or obligations hereunder shall be assigned by any of
the parties hereto without the prior written consent of the other party.

                                       25
<PAGE>
 
     Section 6.5  Entire Agreement.  The Exhibits and Schedules referred to
herein, whether or not attached hereto, are hereby incorporated in and made a
part of this Agreement as if set forth in full herein. This Agreement
constitutes the sole and entire agreement among the parties hereto with respect
to the subject matter hereof and supersedes all prior arrangements or
understandings with respect thereto; and there are no express or implied
restrictions, agreements, promises, representations, warranties, covenants or
undertakings other than those expressly set forth herein.

     Section 6.6  Severability.  Any provision of this Agreement which is
prohibited or unenforceable in any jurisdiction shall, as to such jurisdiction,
be ineffective to the extent of such prohibition or unenforceability without
invalidating the remaining provisions hereof and any such prohibition or
unenforceability in any jurisdiction shall not invalidate or render
unenforceable such provision in any other jurisdiction.

     Section 6.7  Third Parties.  Except as specifically set forth or referred
to herein, nothing herein expressed or implied is intended or shall be construed
to confer upon or give any entity, other than the parties hereto and their
successors and permitted assigns, any rights or remedies under or by reason of
this Agreement.

     Section 6.8  Counterparts.  This Agreement may be executed in two or more
counterparts all of which shall be considered one and the same agreement and
each of which shall be deemed an original.

     Section 6.9  Governing Law.  This Agreement shall be governed by and
construed in accordance with the laws of the State of New York, without giving
effect to principles of conflicts of law thereunder.

                                      26
<PAGE>
 
     IN WITNESS WHEREOF, each of the parties hereto has caused this Agreement to
be duly executed as of the day and year first above written.


ARIMETCO INTERNATIONAL INC.


By: /s/ John A. McKinney
   ------------------------------------
   Name:  John A. McKinney
   Title: Senior Vice President


ATLAS CORPORATION


By: /s/ Gerald E. Davis
   ------------------------------------
   Name:  Gerald E. Davis
   Title: President

                                       27