Exhibit 10.12

                           ASSIGNMENT OF NET PROFITS
                           -------------------------
                                    INTEREST
                                    --------

KNOW ALL MEN BY THESE PRESENTS, THAT:

THIS ASSIGNMENT,  dated as of the Effective Date as herein defined,  is executed
by Earth  Sciences,  Inc., a Colorado  corporation,  ESI Resources  Limited,  an
Alberta  corporation,  and Earth Sciences Extraction Company, an Alberta limited
partnership, whose mailing address is c/o Earth Sciences, Inc., 910 12th Street,
Golden, Colorado 80401 (collectively, the "Assignor"), to Yankee Atomic Electric
Company and Vermont Yankee  Nuclear Power  Corporation,  jointly,  whose mailing
addresses  are c/o Yankee  Atomic  Electric  Company,  580 Main Street,  Bolton,
Massachusetts 01740 (collectively, the "Assignee"). Capitalized terms shall have
the meaning set forth above and in Article VIII hereof.

                              ARTICLE I CONVEYANCE
                                        ----------

Assignor,  for and in consideration of the sum of One Hundred Dollars  ($100.00)
and other good and valuable  consideration in hand paid by Assignee to Assignor,
the receipt  and  sufficiency  of which are hereby  acknowledged,  has  GRANTED,
BARGAINED,  SOLD, CONVEYED,  ASSIGNED and DELIVERED,  and by these presents does
hereby  GRANT,  BARGAIN,  SELL,  CONVEY,  ASSIGN and  DELIVER,  the Net  Profits
Interest unto ASSIGNEE.

TO HAVE AND TO HOLD the Net Profits Interest, together with all and singular the
rights  and  appurtenances  thereunto,   subject,  however,  to  the  terms  and
provisions  of the Permitted  Agreements  and Burdens and this  Conveyance;  and
Assignor does by these  presents bind and obligate  itself,  its  successors and
assigns,  to WARRANT  and  FOREVER  DEFEND,  all and  singular  the Net  Profits
Interest unto the Assignee,  its  successors  and assigns,  against every person
whomsoever,  lawfully  claiming  or to claim the same or any part  thereof,  by,
through or under the Assignor, but not otherwise.

                         ARTICLE II RECORDS AND REPORTS
                                    -------------------

2 01.  Books and  Records.  The Assignor  shall at all times  maintain  true and
correct  books and records  sufficient  to determine  the Net Profits  Interest,
including,  but not limited to,  accounts to which Gross  Revenues and Costs and
Expenses are credited and charged and from which Net Income is determined.  Such
books and records shall be maintained in accordance with GAAP.

2.02.  Inspections.  The books and records  referred to in Section 2.01 shall be
open for inspection,  copying and audit at the offices of ESI Resources Limited,
3077 Shepard Place S.E., Calgary, Alberta T2H 2H4 during normal business hours.

2.03.  Annual  Statements.  Within ninety (90) days next  following the close of
each calendar year,  Assignor  shall deliver to the Assignee,  together with any
payment  due  under  Section  3.01  below,  a  detailed  statement  showing  the
computation  of  Net  Income  attributable  to  such  year,   accompanied  by  a
certificate  of the chief  financial  officer of ESI stating that such statement
has been  prepared in accordance  with this  Agreement and that such person does
not know of any  inaccuracy  therein.  The statement  will be  accompanied by an
audit report on Earth Science,  Inc.'s year end financial  statement prepared by
Earth Science, Inc.'s independent certified public accountants.

2.04.  Assignee's  Exceptions  to Annual  Statements.  If  Assignee  shall  take
exception  to any item or items  included in the annual  statements  rendered by
Assignor,  Assignee shall notify  Assignor in writing within two (2) years after
the  receipt of  thereof,  setting  forth in such  notice the  specific  charges
complained  of and to which  exception  is taken or the specific  credits  which
should  have been made and  allowed,  and with  respect to such  complaints  and
exceptions as are justified, adjustment shall be made. If Assignee shall fail to
give Assignor notice of such  complaints and exceptions  prior to the expiration
of such two year period,  then the statements as originally rendered by Assignor
shall be deemed to be correct as rendered.

                                       32
<PAGE>


                              ARTICLE III PAYMENT
                                          -------

3.01.  Payment. On or before the last Business Day in the month of March in each
year  commencing in 1998,  Assignor  shall pay to Assignee  (except as otherwise
provided in Article  VII) an amount  equal to the Net Profits  Interest  for the
prior  calendar  year or pro rata part  thereof  less Net Profits  Taxes paid or
payable by  Assignor  and/or  its  Affiliates  or other  Person on behalf of the
Assignee.  Such payment shall be  accompanied  by the statement and  certificate
required under Section 2.03 hereof. All payments shall be in U.S. dollars.

3.02. Interest on Past Due Payments. Any amount not paid by Assignor to Assignee
when due shall  bear,  and  Assignor  will pay,  interest at the rate of 18% per
annum, but not in excess of the maximum amount allowed by law.

3.03. Overpayment. If at any time Assignor inadvertently pays Assignee more than
the amount due, Assignee shall not be obligated to return such overpayment,  but
the amount or amounts  otherwise  payable for any  subsequent  period or periods
shall be reduced by such overpayment, without interest.

                      ARTICLE IV NON-LIABILITY OF ASSIGNEE
                                 -------------------------

In no event shall Assignee be liable or responsible in any way for any Costs and
Expenses or other costs or liabilities  incurred by Assignor in connection  with
the Facility.

                        ARTICLE V OPERATION OF FACILITY
                                  ---------------------

5.01.  Prudency  Standard.  Assignor  agrees that it will conduct or cause to be
conducted,  the  development,  maintenance  and  operation of the Facility  with
reasonable and prudent business judgment and in accordance with good practices.

5.02. Abandonment of Facility.  Nothing herein contained shall obligate Assignor
to continue to maintain or attempt to maintain the Facility  when, in Assignor's
sole opinion, the Facility is incapable of producing a profit to the Assignor.

5.03. Insurance.  Assignor shall maintain, or cause to be maintained,  insurance
in such  amounts  and  covering  such risk as is usually  carried  by  companies
engaged in  similar  business  and  owning  similar  properties.  All  insurance
required by this Section 5.03 shall be maintained with responsible and reputable
insurance  companies  or  associations,  and may  contain  such  deductibles  as
Assignor deems appropriate.

                             ARTICLE VI ASSIGNMENTS
                                        -----------

6.01. Assignment by Assignor. Assignor shall not have the right to assign, sell,
transfer,  convey,  mortgage or pledge any interest in the Facility  unless made
expressly  subject to the Net Profits  Interest and the terms and  provisions of
this Conveyance.

6.02.  Assignment by Assignee.  Assignee has the right to assign the Net Profits
Interest in whole or in part. However, no such assignment will affect the method
of  computing  Net  Income,  and if more than one  Person  becomes  entitled  to
participate in the Net Profits Interest, Assignor may withhold the furnishing of
any information provided for in ARTICLE II from such other Person until Assignor
is  furnished a  recordable  instrument  executed by or binding upon all Persons
interested in the Net Profits Interest  designating one Person who is to receive
such information.

6.03. Change in Ownership. No change of ownership or right to receive payment of
the Net Profits Interest, or of any part thereof, however accomplished, shall be
binding upon  Assignor  until notice  thereof  shall have been  furnished by the
Person  claiming  the benefit  thereof,  and then only with  respect to payments
thereafter made.  Notice of sale or assignment shall consist of a certified copy
of the recorded instrument accomplishing the same; notice of change of ownership
or right to receive payment accomplished in any manner (for example by reason of
incapacity,  death or dissolution) shall consist of certified copies of recorded


                                       33
<PAGE>

documents and complete  proceedings legally binding and conclusive of the rights
of all parties. Until such notice shall have been furnished to Assignor as above
provided,  the payment or tender of all sums payable on the Net Profits Interest
may be made in the manner  provided  herein  precisely  as if no such  change in
interest ownership or right to receive payment has occurred.  The kind of notice
herein  provided  shall be  exclusive,  and no other  kind,  whether  actual  or
constructive, shall be binding on Assignor.

6.04. Rights of Mortgagee or Trustee.  If the Assignee shall at any time execute
a mortgage or deed of trust  covering  all or part of the Net Profits  Interest,
the  mortgagee(s)  or trustee(s)  therein named or the holder of any  obligation
secured  thereby shall be entitled,  to the extent the mortgage or deed of trust
so  provides,  to  exercise  all the  rights,  remedies,  powers and  privileges
conferred  upon the  Assignee  by the  terms of this  Conveyance  and to give or
withhold all consents required to be obtained hereunder by the Assignee, but the
provisions of this Section 6.04 shall in no way be deemed or construed to impose
upon the Assignor any  obligation or liability  undertaken by the Assignee under
such mortgage or deed of trust or under the obligation secured thereby.

                         ARTICLE VII REPURCHASE OPTION
                                     -----------------

Assignor shall have the option to repurchase  the Net Profits  Interest from the
Assignee or its successors  and assigns at any time prior to the  termination of
the Net Profits  Interest by paying the Assignee or its  successors  and assigns
the sum of (a)  $3,000,000  plus (b) an additional  $50,000 for each January 1st
following the date of this Conveyance. In addition,  Assignor shall pay Assignee
on March 30 of the calendar  year  following  the year in which this  repurchase
option is  exercised  an amount  equal to (a) the Net Profits for the  preceding
calendar year  multiplied by (b) a fraction  equal to the numeric  equivalent of
the month in which the repurchase option is exercised divided by 12.

Notwithstanding  anything in this Article to the  contrary,  the Assignor  shall
never be required  to pay  Assignee  and its  successors  and assigns  more than
$3,250,000 to repurchase the Net Profits Interest.

                            ARTICLE VIII DEFINITIONS
                                         -----------

The following  words,  terms or phrases have the following  meaning when used in
this Agreement:

"Affiliate"  means as to any Person,  any Person  controlling,  controlled by or
under  common  control  with such  Person,  with the  concept of control in such
context meaning the possession,  directly or indirectly,  of the power to direct
or cause the  direction  of the  management  and  policies of  another,  whether
through the ownership of voting securities, by contract or otherwise.

"Assignee"  means the  Assignee  while it owns an  interest  in the Net  Profits
Interest,  and any other Person or Persons who subsequently  acquire legal title
to-all or any portion of the Net Profits Interest.

"Assignor"  means the Assignor  while it owns all or part of the Facility  other
than a royalty or profits interest,  and any other Person or Persons who acquire
all or any part of the Facility other than a royalty or profits interest.

"Business  Day"  means any day which is not a  Saturday,  Sunday or other day in
which national banking  institutions in the City of Denver,  Colorado are closed
as authorized or required by law.

"Conveyance" means this Assignment of Net Profits Interest.

"Costs  and  Expenses"  means the sum of the  following  amounts  related to the
Facility  determined in accordance  with GAAP from and after the Effective  Date
(which  shall be counted  only once even though they may be covered by more than
one of the subparagraphs or clauses of this definition):

(1) all actual cash expenditures and reasonable  accruals by the Assignor or its
Affiliates in connection with the operation of the Facility, including by way of
example and not limitation, all costs for any materials, processing, production,
haulage,   storage,   rentals,   assessments,   testing,  selling,  general  and
administrative costs directly relating to the Facility,  supplies, materials and
maintenance,  all  payments  of any  kind  to  Western  Cooperative  Fertilizers
Limited,  all taxes directly related to the Facility or the production therefrom
except  income  taxes,  all costs of  employees  utilized  on or for the  direct
benefit of the  Facility  and  operations  thereof,  including  wages,  plans of


                                       34
<PAGE>


deferred compensation, other employee contributions, and all additional benefits
such as insurance,  retirement and services  calculated on a cost (no profit and
including  only those bonuses that are reasonable and customary in the industry)
basis to Assignor and/or its Affiliates, including appropriate overhead charges,
all  costs  of  professional  consultants,  accounting  and  legal  services  or
independent  contractors  insofar  as  they  relate  directly  to the  Facility;
insurance;  utilities,  including  power and water,  and all other  costs of the
Assignor and/or its Affiliates in connection with the preservation and operation
of the Facility;

(2) Production Taxes related to the Facility;

(3) any amounts paid or accrued by the Assignor and/or its  Affiliates,  whether
as refund,  interest or penalty,  to a  purchaser  because the amount  initially
received by the  Assignor  and/or its  Affiliates  as sales  price was more,  or
allegedly more, than permitted by the terms of any applicable contract, statute,
regulation, order, decree or other obligations related to the Facility; and

(4) amounts paid by the Assignor and/or its Affiliates on and in accordance with
any  Permitted  Agreements  and Burdens,  interest paid by the Assignor to third
parties  on   indebtedness   incurred  in  connection   with  the  Facility  and
depreciation and amortization at a rate no greater than a straight line basis of
or related to the Facility.

"Effective  Date" means 12:01  a.m.,  Calgary  time on the first day of the next
succeeding  month after  exercise by ESI of the option  described  in the Option
Agreement,  dated as of 20, 1997 to which Earth  Sciences,  Inc. and Yankee are,
among others, parties.

"Facility" means the Assignor's solvent extraction  facility located in Calgary,
Alberta, the legal description of which is as follows:

MERIDIAN 4 RANGE 29 TOWNSHIP 23
SECTION 16
THAT PORTION OF THE  NORTHEAST  QUARTER  WHICH LIES TO THE SOUTH AND WEST OF THE
ROADWAY ON PLAN  5170EZ AND TO THE SOUTH AND EAST OF THE LAND  COMPRISED  WITHIN
6460AR CONTAINING 53.7 HECTARES (132.67 ACRES) MORE OR LESS EXCEPTING THE STREET
WIDENING ON PLAN 8311428  CONTAINING  0.164  HECTARES  (0.41 ACRES) MORE OR LESS
EXCEPTING THEREOUT ALL MINES AND MINERALS; and
PLAN 6460AR
BLOCK "X" AND BLOCK "Y"
EXCEPTING OUT OF SAID BLOCK "Y" THE RIGHT OF WAY ON PLAN RW543  CONTAINING 0.526
HECTARES (1.30 ACRES) MORE OR LESS EXCEPTING THEREOUT ALL MINES AND MINERALS AND
THE RIGHT TO WORK THE SAME.

"GAAP" means generally accepted accounting principles.

"Gross Revenues" means the sum of the following amounts determined in accordance
with GAAP from and after the  Effective  Date (which items shall be counted only
once even  though they may be covered by more than one of the  subparagraphs  or
clauses of this definition):

(1) An  amount  equal to all  sales of  products  from the  Facility  after  the
Effective Date recognized under GAAP by the Assignor and/or its Affiliates;

(2) The income from all insurance less costs of collection, judgments and claims
(including   settlements  thereof),   recognized  by  the  Assignor  and/or  its
Affiliates involving the Facility to the extent such income is not actually used
or committed  for use in repairing,  rebuilding  or replacing any property,  the
loss, damage, taking or condemning of which gave rise to such judgment or claim;
and



                                       35
<PAGE>


(3) All other  monies and things of value  recognized  as income by the Assignor
and/or its  Affiliates by virtue of the  ownership of the Facility,  except that
the income from the sale by the Assignor  and/or its  Affiliates of any interest
in the  Facility  shall not be included  inGross  Revenues in the event that the
Assignor and/or its Affiliates should hereafter sell any part of its interest in
the Facility subject to the Net Profits Interest herein assigned.

"Net Income" for any period means the excess of Gross Revenues recognized during
such period over the Costs and Expenses recognized during such period.

"Net Loss " at any calendar year end date means an amount equal to the excess of
Costs and Expenses over Gross Revenues for such period.  Net Loss will not carry
forward or carry back.

"Net Profits Interest" means 10% of the Net Income.

"Net Profits  Taxes" means all windfall  profit taxes,  state  severance  taxes,
excise taxes, ad valorem taxes, income taxes and all other taxes or governmental
charges  which are  attributable  to the Net  Profits  Interest,  to Net  Income
derived  by the  Assignee  therefrom,  or to both and as to which  the  Assignor
and/or its Affiliates is required to withhold and pay over or otherwise  account
to any taxing authority.

"Non-Affiliate"  means,  as to the party  specified,  any  Person  who is not an
Affiliate of such party.

"Permitted Agreements and Burdens" means all agreements,  whenever entered into,
relating  to the  borrowing  of  monies  for use at or in  connection  with  the
Facility;  and, if consented to by the Assignee,  all other  agreements  entered
into after the Effective Date.

"Person" means any individual, corporation,  partnership, trust, estate or other
entity or organization.

"Production  Taxes" means (a) all windfall profit taxes,  state,  provincial and
local severance taxes and all other taxes,  excluding  income taxes, and (b) all
ad  valorem  taxes and other  taxes,  excluding  income  taxes,  imposed  on the
Facility or Assignor and/or its Affiliates' interest therein.

                            ARTICLE IX MISCELLANEOUS
                                       -------------

9.01.  Term. This Conveyance shall remain in force and effect until the earliest
of (i) the tenth  anniversary  following the Effective Date; (ii) payment by the
Assignor of a total of $4,850,000 pursuant to the terms hereof or by prepayment;
or (iii) the date on which the repurchase option described herein is exercised.

9.02. Further  Assurances.  Should any additional  instruments of assignment and
conveyance  be required to describe  more  specifically  any  interests  subject
hereto,  Assignor and Assignor  agree to execute and deliver the same.  Also, if
any other or additional instruments are required in connection herewith in order
to comply with  applicable  laws or  regulations,  Assignor  and  Assignee  will
execute and deliver the same.

9.03. Notices. All notices, statements,  payments and communications between the
parties hereto shall be deemed to have been sufficiently  given and delivered if
enclosed  in a post paid  wrapper  and  deposited  in the  United  States  mails
directed,  or if personally  delivered or  telecopied,  to the party to whom the
same is  directed  or to be  furnished  or made at the  respective  address,  as
follows:

ASSIGNOR:

         c/o Earth Sciences, Inc.
         910 12th Street
         Golden, CO 80401
         Tel. No. (303) 279-7641
         Fax No. (303) 279-1180

ASSIGNEE:
         c/o Yankee Atomic Electric Company
         580 Main Street
         Bolton, Massachusetts 01740
         Tel. No. (508) 779-6711
         Fax No. (508) 568-3703



                                       36
<PAGE>


Either  party or the  successors  or  assignees  of the  interest  or  rights or
obligations of either party  hereunder may change its address or designate a new
or different  address or addresses for the purposes  hereof by a similar  notice
given or directed to all parties interested hereunder at the time.

9.04. Binding Effect. This Conveyance shall bind and inure to the benefit of the
successors and assigns of Assignor and Assignee.

9.05.  Governing Law. The validity,  effect and  construction of this Conveyance
shall be governed by the laws of Colorado.

9.06.  Headings.  Article and Section  headings used in this  Conveyance are for
convenience only and shall not affect the construction of this Conveyance.

9.07.  Substitution of Warranty.  This instrument is made with full substitution
and  subrogation  of  Assignee  in and to all  covenants  of  warranty by others
heretofore  given or made with  respect to the  Facility or any part  thereof or
interest therein.

9.08.  Counterpart  Execution.  This  Conveyance  is being  executed in multiple
original  counterparts,  all of which are identical.  Every  counterpart of this
Conveyance  shall be  deemed to be an  original  for all  purposes  and all such
counterparts together shall constitute one and the same Conveyance.

IN WITNESS  WHEREOF,  the parties have caused this  Conveyance to be executed in
their  respective  names and their  corporate  seals to be  affixed  hereto  and
attested by their proper signatory  officers thereunto  authorized,  in multiple
originals, as of the Effective Date.

Earth Sciences, Inc.

By  /s/ Mark H. McKinnies
-----------------------------------
President

ESI Resources Limited

By  /s/ Mark H. McKinnies
-----------------------------------
President

Earth Sciences Extraction Company
by ESI Resources Limited, general partner

By  /s/ Mark H. McKinnies
-----------------------------------
President

Yankee Atomic Electric Company

By  /s/ Thomas W. Bennett Jr.
-----------------------------------
Authorized Officer
Chief Financial Officer

Vermont Yankee Nuclear Power Corporation

By Ross P. Barkhurst
-----------------------------------
Authorized Officer
President



                                       37
<PAGE>


STATE OF COLORADO    )
                           ) ss.
COUNTY OF JEFFERSON  )

The foregoing  instrument was acknowledged  before me this 20th day of October ,
1997, by Mark H. McKinnies as President of Earth Sciences, Inc.

Witness my hand and official seal.

My Commission Expires:  12/14/2000
                                          /s/ Christy L Zapp
                                          --------------------------------------
                                          Notary Public
                                          Name: Christy L Zapp
                                          Address: 11957 W. 71st Dr. Arvada, CO

         STATE OF COLORADO          )
                                      ) ss.
         COUNTY OF JEFFERSON        )

The foregoing  instrument was  acknowledged  before me this 20th day of October,
1997,  by Mark H.  McKinnies as President  of ESI  Resources  Limited on its own
behalf and as general partner of Earth Sciences Extraction Company.

Witness my hand and official seal.

My Commission Expires:  12/14/2000
                                          /s/ Christy L Zapp
                                          --------------------------------------
                                          Notary Public
                                          Name: Christy L Zapp
                                          Address: 11957 W. 71st Dr. Arvada, CO



COMMONWEALTH OF MASSACHUSETTS )
                                 ) ss.
COUNTY OF WORCESTER           )

The foregoing  instrument was  acknowledged  before me this 24th day of October,
1997,  by Thomas W. Bennett  Jr., as Chief  financial  Officer of Yankee  Atomic
Electric Company.

Witness my hand and official seal.

My Commission Expires:  8/28/2003
                                          /s/ Maureen E. Maynard
                                          --------------------------------------
                                          Notary Public
                                          Name: Maureen E. Maynard
                                          Address: 10 Winward Drive,
                                                   Oxford, MA  01540


STATE OF VERMONT   )
                     ) ss.
COUNTY OF WINDHAM  )



                                       38
<PAGE>


The foregoing  instrument was  acknowledged  before me this 28th day of October,
1997 by Ross  P.  Barkhurst,  as  President  of  Vermont  Yankee  Nuclear  Power
Corporation.

         Witness my hand and official seal.
         My Commission Expires:  2/10/99

                                              /s/  Judith A. Harris
                                             -----------------------------------
                                             Notary Public
                                             Name: Judith A. Harris
                                             Address: 228 MHP W. Brattleboro,
                                                      VT   05301


                                       39