Exhibit 4.3


 


[Form of Warrant Certificate]


 


[FACE]


 


Number


 


Warrants


 


THIS WARRANT SHALL BE VOID IF NOT EXERCISED
PRIOR TO


THE EXPIRATION OF THE EXERCISE PERIOD PROVIDED
FOR


IN THE WARRANT AGREEMENT DESCRIBED BELOW


 


SEAPORT CALIBRE MATERIALS ACQUISITION CORP.


Incorporated Under the Laws of the State of Delaware


 


CUSIP 812204 113


Warrant Certificate


 


This Warrant Certificate certifies that 
                   , or registered assigns, is the registered holder of warrant(s) evidenced
hereby (the “Warrants” and each, a “Warrant”) to purchase shares of Class A common
stock, $0.0001 par value per share (“Common Stock”), of Seaport Calibre Materials Acquisition
Corp., a Delaware corporation (the “Company”). Each whole Warrant entitles the holder, upon exercise during
the period set forth in the Warrant Agreement referred to below, to receive from the Company that number of fully paid and non-assessable
shares of Common Stock as set forth below, at the exercise price (the “Warrant Price”) as
determined pursuant to the Warrant Agreement, payable in lawful money (or through “cashless exercise”
as provided for in the Warrant Agreement) of the United States of America upon surrender of this Warrant Certificate and payment of the
Warrant Price at the office or agency of the Warrant Agent referred to below, subject to the conditions set forth herein and in the Warrant
Agreement. Defined terms used in this Warrant Certificate but not defined herein shall have the meanings given to them in the Warrant
Agreement.


 


Each whole Warrant is initially
exercisable for one fully paid and non-assessable share of Common Stock. No fractional shares will be issued upon exercise of any Warrant.
If, upon the exercise of Warrants, a holder would be entitled to receive a fractional interest in a share of Common Stock, the Company
will, upon exercise, round down to the nearest whole number the number of shares of Common Stock to be issued to the Warrant holder. The
number of shares of Common Stock issuable upon exercise of the Warrants is subject to adjustment upon the occurrence of certain events
set forth in the Warrant Agreement.


 


The initial Warrant Price
per share of Common Stock for any Warrant is equal to $11.50 per whole share. The Warrant Price is subject to adjustment upon the occurrence
of certain events set forth in the Warrant Agreement.


 


Subject to the conditions
set forth in the Warrant Agreement, the Warrants may be exercised only during the Exercise Period and to the extent not exercised by the
end of such Exercise Period, such Warrants shall become void.


 


Reference is hereby made to
the further provisions of this Warrant Certificate set forth on the reverse hereof and such further provisions shall for all purposes
have the same effect as though fully set forth at this place.


 


This Warrant Certificate shall
not be valid unless countersigned by the Warrant Agent, as such term is used in the Warrant Agreement.


 


This Warrant Certificate shall
be governed by and construed in accordance with the internal laws of the State of New York, without regard to conflicts of laws principles
thereof.



 


	 	SEAPORT CALIBRE MATERIALS ACQUISITION CORP.
	 	 	 
	 	By:	          
	 	Name: 	 
	 	Title:	 
	 	 	 
	 	CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Warrant Agent
	 	 	 
	 	By:	 
	 	Name:	 
	 	Title:	 


 






     


     


    

 


[Form of Warrant Certificate]


 


[Reverse]


 


The Warrants evidenced by
this Warrant Certificate are part of a duly authorized issue of Warrants entitling the holder on exercise to receive shares of Common
Stock and are issued or to be issued pursuant to a Warrant Agreement dated as of _____, 2021 (the “Warrant Agreement”),
duly executed and delivered by the Company to Continental Stock Transfer & Trust Company, a New York corporation, as warrant agent
(the “Warrant Agent”), which Warrant Agreement is hereby incorporated by reference in and
made a part of this instrument and is hereby referred to for a description of the rights, limitation of rights, obligations, duties and
immunities thereunder of the Warrant Agent, the Company and the holders (the words “holders” or “holder”
meaning the Registered Holders or Registered Holder, respectively) of the Warrants. A copy of the Warrant Agreement may be obtained by
the holder hereof upon written request to the Company. Defined terms used in this Warrant Certificate but not defined herein shall have
the meanings given to them in the Warrant Agreement.


 


Warrants may be exercised
at any time during the Exercise Period set forth in the Warrant Agreement. The holder of Warrants evidenced by this Warrant Certificate
may exercise them by surrendering this Warrant Certificate, with the form of election to purchase set forth hereon properly completed
and executed, together with payment of the Warrant Price as specified in the Warrant Agreement (or through “cashless exercise”
as provided for in the Warrant Agreement) at the principal corporate trust office of the Warrant Agent. In the event that upon any exercise
of Warrants evidenced hereby the number of Warrants exercised shall be less than the total number of Warrants evidenced hereby, there
shall be issued to the holder hereof or his, her or its assignee, a new Warrant Certificate evidencing the number of Warrants not exercised.


 


Notwithstanding anything else
in this Warrant Certificate or the Warrant Agreement, no Warrant may be exercised unless at the time of exercise (i) a registration statement
covering the shares of Common Stock to be issued upon exercise is effective under the Securities Act and (ii) a prospectus thereunder
relating to the shares of Common Stock is current, except through “cashless exercise” as provided for in the Warrant Agreement.


 


The Warrant Agreement provides
that upon the occurrence of certain events the number of shares of Common Stock issuable upon exercise of the Warrants set forth on the
face hereof may, subject to certain conditions, be adjusted. If, upon exercise of a Warrant, the holder thereof would be entitled to receive
a fractional interest in a share of Common Stock, the Company shall, upon exercise, round down to the nearest whole number of shares of
Common Stock to be issued to the holder of the Warrant.


 


Warrant Certificates, when
surrendered at the principal corporate trust office of the Warrant Agent by the Registered Holder thereof in person or by legal representative
or attorney duly authorized in writing, may be exchanged, in the manner and subject to the limitations provided in the Warrant Agreement,
but without payment of any service charge, for another Warrant Certificate or Warrant Certificates of like tenor evidencing in the aggregate
a like number of Warrants.


 


Upon due presentation for
registration of transfer of this Warrant Certificate at the office of the Warrant Agent a new Warrant Certificate or Warrant Certificates
of like tenor and evidencing in the aggregate a like number of Warrants shall be issued to the transferee(s) in exchange for this Warrant
Certificate, subject to the limitations provided in the Warrant Agreement, without charge except for any tax or other governmental charge
imposed in connection therewith.


 


The Company and the Warrant
Agent may deem and treat the Registered Holder(s) hereof as the absolute owner(s) of this Warrant Certificate (notwithstanding any notation
of ownership or other writing hereon made by anyone), for the purpose of any exercise hereof, of any distribution to the holder(s) hereof,
and for all other purposes, and neither the Company nor the Warrant Agent shall be affected by any notice to the contrary. Neither the
Warrants nor this Warrant Certificate entitles any holder hereof to any rights of a stockholder of the Company.


 






     


     


    

 


Election to Purchase


 


(To Be Executed Upon Exercise of Warrant)


 


The undersigned hereby irrevocably
elects to exercise the right, represented by this Warrant Certificate, to receive               
   shares of Common Stock and herewith tenders payment for such shares of Common Stock to the order of Seaport Calibre Materials Acquisition
Corp. (the “Company”) in the amount of $         in accordance with the terms hereof.
The undersigned requests that a certificate for such shares of Common Stock be registered in the name of         
        , whose address is                  and that such shares of Common
Stock be delivered to                                  
whose address is                 . If said number of shares of Common Stock is less than
all of the shares of Common Stock purchasable hereunder, the undersigned requests that a new Warrant Certificate representing the remaining
balance of such shares of Common Stock be registered in the name of                 , whose
address is                          and that such Warrant Certificate
be delivered to                 , whose address is           
      .


 


In the event that the Warrant
has been called for redemption by the Company pursuant to Section 6 of the Warrant Agreement and the Company has required
cashless exercise pursuant to Section 6.4 of the Warrant Agreement, the number of shares of Common Stock that this Warrant
is exercisable for shall be determined in accordance with subsection 3.3.1(b) and Section 6.4 of the
Warrant Agreement.


 


In the event that the Warrant
has been called for redemption by the Company pursuant to Section 6.2 of the Warrant Agreement and a holder thereof elects to exercise
its Warrant pursuant to a Make-Whole Exercise, the number of Ordinary Shares that this Warrant is exercisable for shall be determined
in accordance with subsection 3.3.1(c) or Section 6.2 of the Warrant Agreement, as applicable.


 


In the event that the Warrant
is a Private Placement Warrant or a Working Capital Warrant that is to be exercised on a “cashless” basis pursuant to subsection
3.3.1(c) of the Warrant Agreement, the number of shares of Common Stock that this Warrant is exercisable for shall be determined
in accordance with subsection 3.3.1(c) of the Warrant Agreement.


 


In the event that the Warrant
is to be exercised on a “cashless” basis pursuant to Section 7.4 of the Warrant Agreement, the number of
shares of Common Stock that this Warrant is exercisable for shall be determined in accordance with Section 7.4 of the
Warrant Agreement.


 


In the event that the Warrant
may be exercised, to the extent allowed by the Warrant Agreement, through cashless exercise (i) the number of shares of Common Stock that
this Warrant is exercisable for would be determined in accordance with the relevant section of the Warrant Agreement which allows for
such cashless exercise and (ii) the holder hereof shall complete the following: The undersigned hereby irrevocably elects to exercise
the right, represented by this Warrant Certificate, through the cashless exercise provisions of the Warrant Agreement, to receive shares
of Common Stock. If said number of shares of Common Stock is less than all of the shares of Common Stock purchasable hereunder (after
giving effect to the cashless exercise), the undersigned requests that a new Warrant Certificate representing the remaining balance of
such shares of Common Stock be registered in the name of                 , whose address
is                          and that such Warrant Certificate be delivered
to                 , whose address is                
..


 


[Signature Page Follows]


 






     


     


    

 


	Date:                , 2021	 
	 	(Signature)
	 	 
	 	 
	 	 
	 	 
	 	(Address)
	 	 
	 	 
	 	(Tax Identification Number)
	Signature Guaranteed:	 
	 	 


 


THE SIGNATURE(S) SHOULD BE GUARANTEED BY AN ELIGIBLE
GUARANTOR INSTITUTION (BANKS, STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS AND CREDIT UNIONS WITH MEMBERSHIP IN AN APPROVED SIGNATURE GUARANTEE
MEDALLION PROGRAM, PURSUANT TO S.E.C. RULE 17Ad-15 UNDER THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED (OR ANY SUCCESSOR RULE)).


 



     


     


    




 


EXHIBIT B


 


LEGEND


 


“THE SECURITIES REPRESENTED BY THIS CERTIFICATE
HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, OR ANY STATE SECURITIES LAWS, AND MAY NOT BE OFFERED, SOLD, TRANSFERRED
OR OTHERWISE DISPOSED OF UNLESS REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND ANY APPLICABLE STATE SECURITIES LAWS OR AN
EXEMPTION FROM REGISTRATION IS AVAILABLE. IN ADDITION, SUBJECT TO ANY ADDITIONAL LIMITATIONS ON TRANSFER DESCRIBED IN THE LETTER AGREEMENT
BY AND AMONG SEAPORT CALIBRE MATERIALS ACQUISITION CORP. (THE “COMPANY”), SEAPORT GLOBAL ASSET MANAGEMENT, LLC, CALIBRE GROUP,
LLC AND THE OTHER PARTIES THERETO, THE SECURITIES REPRESENTED BY THIS CERTIFICATE MAY NOT BE SOLD OR TRANSFERRED PRIOR TO THE DATE THAT
IS THIRTY (30) DAYS AFTER THE DATE UPON WHICH THE COMPANY COMPLETES ITS INITIAL BUSINESS COMBINATION (AS DEFINED IN SECTION 3 OF THE WARRANT
AGREEMENT REFERRED TO HEREIN) EXCEPT TO A PERMITTED TRANSFEREE (AS DEFINED IN SECTION 2 OF THE WARRANT AGREEMENT) WHO AGREES IN WRITING
WITH THE COMPANY TO BE SUBJECT TO SUCH TRANSFER PROVISIONS.


 


SECURITIES EVIDENCED BY THIS CERTIFICATE AND SHARES
OF CLASS A COMMON STOCK OF THE COMPANY ISSUED UPON EXERCISE OF SUCH SECURITIES SHALL BE ENTITLED TO REGISTRATION RIGHTS UNDER A REGISTRATION
RIGHTS AGREEMENT TO BE EXECUTED BY THE COMPANY.”