SCHEDULE 13G

Amendment No. 3
Martin Marietta Materials Incorporated
common stock
Cusip # 573284106

Cusip # 573284106
Item 1:	Reporting Person - FMR Corp.
Item 4:	Commonwealth of Massachusetts
Item 5:	1,750,100
Item 6:	0
Item 7:	4,179,714
Item 8:	0
Item 9:	4,701,124
Item 11:	10.05%
Item 12:	    HC

Cusip # 573284106
Item 1:	Reporting Person - Edward C. Johnson 3d
Item 4:	United States of America
Item 5:	0
Item 6:	0
Item 7:	4,701,124
Item 8:	0
Item 9:	4,701,124
Item 11:	10.05%
Item 12:	IN

Cusip # 573284106
Item 1:	Reporting Person - Abigail P. Johnson
Item 4:	United States of America
Item 5:	0
Item 6:	0
Item 7:	4,701,124
Item 8:	0
Item 9:	4,701,124
Item 11:	10.05%
Item 12:	IN


SCHEDULE 13G - TO BE INCLUDED IN STATEMENTS
FILED PURSUANT TO RULE 13d-1(c)

Item 1(a).	Name of Issuer:

		Martin Marietta Materials Incorporated

Item 1(b).	Name of Issuer's Principal Executive Offices:

		2710 Wycliff Road
		Raleigh, NC 27607-3033

Item 2(a).	Name of Person Filing:

		FMR Corp.

Item 2(b).	Address or Principal Business Office or, if None,
Residence:

		82 Devonshire Street, Boston, Massachusetts  02109

Item 2(c).	Citizenship:

		Not applicable

Item 2(d).	Title of Class of Securities:

		common stock

Item 2(e).	CUSIP Number:

		573284106

Item 3.	This statement is filed pursuant to Rule 13d-1(c).

		Not applicable

Item 4.	Ownership

	(a)	Amount Beneficially Owned:	4,701,124

	(b)	Percent of Class:	10.05%

	(c)	Number of shares as to which such person has:

	(i)	sole power to vote or to direct the vote:	1,750,100

	(ii)	shared power to vote or to direct the vote:	0

	(iii)	sole power to dispose or to direct the disposition of:
	4,179,714

	(iv)	shared power to dispose or to direct the disposition of:
	0


Item 5.	Ownership of Five Percent or Less of a Common Stock.

	Not applicable.

Item 6.	Ownership of More than Five Percent on Behalf of Another
Person.

	Various persons have the right to receive or the power to direct
the receipt of dividends from, or the proceeds from the sale of, the
common stock of Martin Marietta Materials Incorporated.  No one
person's interest in the common stock of Martin Marietta Materials
Incorporated is more than five percent of the total outstanding common
stock.

Item 7.	Identification and Classification of the Subsidiary Which
Acquired the Security Being Reported on By the Parent Holding Company.

	See attached Exhibit(s) A, B, and C.

Item 8.	Identification and Classification of Members of the Group.

	Not Applicable. See attached Exhibit A.

Item 9.	Notice of Dissolution of Group.

	Not applicable.

Item 10.	Certification.

	By signing below I certify that, to the best of my knowledge and
belief, the securities referred to above were not acquired and are not
held for the purpose of or with the effect of changing or influencing
the control of the issuer of the securities and were not acquired and
are not held in connection with or as a participant in any transaction
having that purpose or effect.

Signature

	After reasonable inquiry and to the best of my knowledge and
belief, I certify that the information set forth in this Schedule 13G
in connection with FMR Corp.'s beneficial ownership of the common stock
of Martin Marietta Materials Incorporated at July 20, 2000 is true,
complete and correct.


	July 24, 2000
Date




Signature



	Eric D. Roiter
	Duly authorized under Power of Attorney
	dated December 30, 1997, by and on behalf
	of FMR Corp. and its direct and indirect
	subsidiaries.



SCHEDULE 13G - TO BE INCLUDED IN STATEMENTS
FILED PURSUANT TO RULE 13d-1(c)

	Pursuant to the instructions in Item 7 of Schedule 13G, Fidelity
Management & Research Company ("Fidelity"), 82 Devonshire Street,
Boston, Massachusetts 02109, a wholly-owned subsidiary of FMR Corp. and
an investment adviser registered under Section 203 of the Investment
Advisers Act of 1940, is the beneficial owner of 2,429,614 shares or
5.20% of the common stock outstanding of Martin Marietta Materials
Incorporated ("the Company") as a result of acting as investment
adviser to various investment companies (the "funds") registered under
Section 8 of the Investment Company Act of 1940.

	Edward C. Johnson 3d, FMR Corp., through its control of Fidelity,
and the funds collectively each has sole power to dispose of the
2,429,614 shares owned by the Funds.

	Neither FMR Corp. nor Edward C. Johnson 3d, Chairman of FMR
Corp., has the sole power to vote or direct the voting of the shares
owned directly by the funds, which power resides with the funds' Boards
of Trustees.  Fidelity carries out the voting of the shares under
written guidelines established by the funds' Boards of Trustees.

	Fidelity Management Trust Company, 82 Devonshire Street, Boston,
Massachusetts 02109, a wholly-owned subsidiary of FMR Corp. and a bank
as defined in Section 3(a)(6) of the Securities Exchange Act of 1934,
is the beneficial owner of 1,750,100 shares or 3.74% of the common
stock outstanding of the Company as a result of its serving as
investment manager of the institutional account(s).

	Edward C. Johnson 3d and FMR Corp., through its control of
Fidelity Management Trust Company, each has sole dispositive power over
1,750,100 shares and sole power to vote or to direct the voting of
1,750,100 shares.

	Strategic Advisers, Inc., 82 Devonshire Street, Boston, MA 02109,
a wholly-owned subsidiary of FMR Corp. and an investment adviser
registered under Section 203 of the Investment Advisers Act of 1940,
provides investment advisory services to individuals. It does not have
sole power to vote or direct the voting of shares of certain securities
held for clients and has sole dispositive power over such securities.
As such, FMR Corp.'s beneficial ownership may include shares
beneficially owned through Strategic Advisers, Inc.

	Members of the Edward C. Johnson 3d family are the predominant
owners of Class B shares of common stock of FMR Corp., representing
approximately 49% of the voting power of FMR Corp.  Mr. Johnson 3d owns
12.0% and Abigail Johnson owns 24.5% of the aggregate outstanding
voting stock of FMR Corp.  Mr. Johnson 3d is Chairman of FMR Corp. and
Abigail P. Johnson is a Director of FMR Corp.  The Johnson family group
and all other Class B shareholders have entered into a shareholders'
voting agreement under which all Class B shares will be voted in
accordance with the majority vote of Class B shares.  Accordingly,
through their ownership of voting common stock and the execution of the
shareholders' voting agreement, members of the Johnson family may be
deemed, under the Investment Company Act of 1940, to form a controlling
group with respect to FMR Corp.

	Fidelity International Limited, Pembroke Hall, 42 Crowlane,
Hamilton, Bermuda, and various foreign-based subsidiaries provide
investment advisory and management services to a number of non-U.S.
investment companies and certain institutional investors.  Fidelity
International Limited is the beneficial owner of 521,410 shares or
1.12% of the common stock outstanding of the Company. Additional
information with respect to the beneficial ownership of Fidelity
International Limited is shown on Exhibit B.

	FMR Corp. and Fidelity International Limited are of the view that
they are not acting as a "group" for purposes of Section 13(d) under
the Securities Exchange Act of 1934 (the "1934 Act") and that they are
not otherwise required to attribute to each other the "beneficial
ownership" of securities "beneficially owned" by the other corporation
within the meaning of Rule 13d-3 promulgated under the 1934 Act.
Therefore, they are of the view that the shares held by the other
corporation need not be aggregated for purposes of Section 13(d).
However, FMR Corp. is making this filing on a voluntary basis as if all
of the shares are beneficially owned by FMR Corp. and Fidelity
International Limited on a joint basis.

EXHIBIT to SCHEDULE 13G - TO BE INCLUDED IN STATEMENTS
FILED PURSUANT TO RULE 13d-1(c)

	Pursuant to instructions in Item 7 of Schedule 13G, this Exhibit
has been prepared to identify Fidelity International Limited, Pembroke
Hall, 42 Crow Lane, Hamilton, Bermuda, a Bermudan joint stock company
incorporated for an unlimited duration by private act of the Bermuda
Legislature (FIL) and an investment adviser to various investment
companies (the "International Funds") and certain institutional
investors, as a beneficial owner of the 521,410 shares or 1.12% of the
common stock outstanding of Martin Marietta Materials Incorporated.

	Prior to June 30, 1980, FIL was a majority-owned subsidiary of
Fidelity Management & Research Company (Fidelity), a wholly-owned
subsidiary of FMR Corp.  On that date, the shares of FIL held by
Fidelity were distributed, as a dividend,  to the shareholders of FMR
Corp.  FIL currently operates as an entity independent of FMR Corp. and
Fidelity.  The International Funds and FIL's other clients, with the
exception of Fidelity and an affiliated company of Fidelity, are non-
U.S. entities.

	A partnership controlled by Edward C. Johnson 3d and members of
his family owns shares of FIL voting stock with the right to cast
approximately 39.89% of the total votes which may be cast by all
holders of FIL voting stock.  Mr. Johnson 3d is Chairman of FMR Corp.
and FIL.  FMR Corp. and FIL are separate and independent corporate
entities, and their Boards of Directors are generally composed of
different individuals.  Other than when one serves as a sub adviser to
the other, their investment decisions are made independently, and their
clients are generally different organizations.

	FMR Corp. and Fidelity International Limited are of the view that
they are not acting as a "group" for purposes of Section 13(d) under
the Securities Exchange Act of 1934 (the "1934 Act") and that they are
not otherwise required to attribute to each other the "beneficial
ownership" of securities "beneficially owned" by the other corporation
within the meaning of Rule 13d-3 promulgated under the 1934 Act.
Therefore, they are of the view that the shares held by the other
corporation need not be aggregated for purposes of Section 13(d).
However, FMR Corp. is making this filing on a voluntary basis as if all
of the shares are beneficially owned by FMR Corp. and Fidelity
International Limited on a joint basis.

	FIL has sole dispositive power over 521,410 shares owned by the
International Funds. FIL has sole power to vote or direct the voting of
521,410 shares of common stock held by the International Funds as
reported above.


SCHEDULE 13G - TO BE INCLUDED IN STATEMENTS
FILED PURSUANT TO RULE 13d-1(c)
RULE 13d-1(f)(1)  AGREEMENT

	The undersigned persons, on July 24, 2000, agree and consent to
the joint filing on their behalf of this Schedule 13G in connection
with their beneficial ownership of the common stock of Martin Marietta
Materials Incorporated at July 20, 2000.

FMR Corp.

By   /s/Eric D. Roiter
	Eric D. Roiter
	Duly authorized under Power of Attorney
	dated December 30, 1997, by and on behalf
	of FMR Corp. and its direct and indirect
	subsidiaries.

Edward C. Johnson 3d

By   /s/Eric D. Roiter
	Eric D. Roiter
	Duly authorized under Power of Attorney
	dated December 30, 1997, by and on behalf
	of Edward C. Johnson 3d.

Abigail P. Johnson

By   /s/Eric D. Roiter
	Eric D. Roiter
	Duly authorized under Power of Attorney
	dated December 30, 1997, by and on behalf
	of Abigail P. Johnson.

Fidelity Management & Research Company

By   /s/Eric D. Roiter
	Eric D. Roiter
	Senior V.P. and General Counsel

Fidelity International Limited

By   /s/Eric D. Roiter
	Eric D. Roiter
	Duly authorized under Power of Attorney
	dated December 30, 1997, by and on behalf
	of Fidelity International Limited and its direct
and indirect subsidiaries.