The Constitution requires the use of local scientific and technical resources (local content requirement) in the case of agreements with foreign-owned companies (limited to 40% foreign ownership) allowing them to exploit mineral resources.
"Only the investment areas and/or activities listed in the attached Eleventh Regular Foreign Investment Negative List shall be reserved for Philippine nationals, subject to the exceptions and conditions indicated therein.
[...]
LIST A: FOREIGN OWNERSHIP IS LIMITED BY MANDATE OF THE CONSTITUTION AND SPECIFIC LAWS
No Foreign Equity [...]
6. Small-scale mining (Sec. 3 of R.A. 7076)
[...]
Up to Forty Percent (40%) Foreign Equity [...]
Exploration, development and utilization of natural resources (Art. XII, Sec. 2 of the Constitution)7 [7  Full foreign participation is allowed through financial or technical assistance agreement entered into with the President (Art. XII, Sec. 2 of the Constitution)][...]" (Eleventh Regular Foreign Investment Negative List (Executive Order No. 65 / 2018))
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"Section 2. All lands of the public domain, waters, minerals, coal, petroleum, and other mineral oils, all forces of potential energy, fisheries, forests or timber, wildlife, flora and fauna, and other natural resources are owned by the State. With the exception of agricultural lands, all other natural resources shall not be alienated. The exploration, development, and utilization of natural resources shall be under the full control and supervision of the State. The State may directly undertake such activities, or it may enter into co-production, joint venture, or production-sharing agreements with Filipino citizens, or corporations or associations at least sixty per centum of whose capital is owned by such citizens. Such agreements may be for a period not exceeding twenty-five years, renewable for not more than twenty-five years, and under such terms and conditions as may be provided by law. [...] The President may enter into agreements with foreign-owned corporations involving either technical or financial assistance for large-scale exploration, development, and utilization of minerals, petroleum, and other mineral oils according to the general terms and conditions provided by law, based on real contributions to the economic growth and general welfare of the country. In such agreements, the State shall promote the development and use of local scientific and technical resources. " (Art XII, Section 2 1987 Constitution of the Republic of The Philippines)
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"Section 3. Definitions. – For purposes of this Act, the following terms shall be defined as follows: [...]
(b) “Small-scale mining” refers to mining activities which rely heavily on manual labor using simple implement and methods and do not use explosives or heavy mining equipment;[...]" (REPUBLIC ACT NO. 7076, June 27, 1991)
Eleventh Regular Foreign Investment Negative List (Executive Order No. 65 / 2018)
Art XII, Sec 2 of the Constitution
REPUBLIC ACT NO. 7076, June 27, 1991
[<a href="https://www.officialgazette.gov.ph/downloads/2018/10oct/20181029-EO-65-RRD.pdf">List</a>],[<a href="http://www.officialgazette.gov.ph/constitutions/1987-constitution/">Constitution</a>],[<a href="https://www.dayananconsulting.com/republic-act-7076/">Act</a>]