[8-K] 5E Advanced Materials, Inc. Reports Material Event

Rhea-AI Filing Summary

5E Advanced Materials, Inc. reported a major upgrade to the mineral resource estimate for its 5E Boron Americas (Fort Cady) Complex in California, effective November 15, 2025. The updated estimate outlines 61.9 million short tons of measured ore containing 9.1 million short tons of in-situ boric acid with an average grade of 8.34% B2O3, and 138.6 million short tons of indicated ore containing 19.2 million short tons of in-situ boric acid at 7.97% B2O3. Combined measured and indicated mineral resource now total 28.3 million tons of boric acid at an average grade of 8.09% B2O3, a 10.8 million ton, or 61%, increase versus the prior estimate, driven by additional lode claims. Measured plus indicated lithium carbonate equivalent resource increased to 328 thousand tons at 0.17% LCE, up 115 thousand tons, or 54%. Previously disclosed mineral reserves and project economics from the company’s Preliminary Feasibility Study remain unchanged.

Positive

• Substantial resource growth: Combined measured plus indicated boric acid resource increased by 10.8 million tons to 28.3 million tons, a 61% uplift, while measured plus indicated lithium carbonate equivalent rose by 115 thousand tons to 328 thousand tons, a 54% increase.

Negative

• None.

Insights

Mining & natural resources analyst

Fort Cady’s measured and indicated resources rise sharply, while reserves and economics stay unchanged.

The company reports substantially higher measured and indicated resources at the Fort Cady boron-lithium project. Combined measured plus indicated boric acid resource is now 28.3 million tons at an average 8.09% B2O3, a 61% increase from the prior estimate, reflecting incorporation of additional lode claims. Measured plus indicated lithium carbonate equivalent rises to 328 thousand tons at 0.17% LCE, a 54% increase.

Because these are mineral resources, not reserves, they indicate larger geological potential but do not by themselves change mine plans or cash flows. The company explicitly states that mineral reserves and project economics from the existing Preliminary Feasibility Study are unchanged and remain current and valid. This anchors the news as geological upside rather than an immediate shift in project value.

The magnitude of the resource uplift is significant for a development-stage project focused on boron and lithium. The update is prepared by a Qualified Person under Regulation S-K 1300, and the mineral resource assumptions, cut-off grade, and pricing assumptions are confirmed as consistent with those used in the Form 10-K for the year ended June 30, 2025. Future technical work and economic studies would determine how much of the expanded resource base can ultimately convert to reserves.

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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): November 15, 2025

5E ADVANCED MATERIALS, INC.

(Exact name of Registrant as Specified in Its Charter)

Delaware			001-41279	87-3426517
(State or Other Jurisdiction of Incorporation)			(Commission File Number)	(IRS Employer Identification No.)
9329 Mariposa Road, Suite 210
Hesperia, California				92344
(Address of Principal Executive Offices)				(Zip Code)

Registrant’s Telephone Number, Including Area Code: (442) 221-0225

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class		Trading Symbol(s)		Name of each exchange on which registered
Common stock, $0.01 par value per share		FEAM		The Nasdaq Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☒

Item 7.01 Regulation FD Disclosure

On November 19, 2025, 5E Advanced Materials, Inc. (the “Company” or “5E”) issued a press release announcing the disclosure of an updated mineral resource estimate, effective November 15, 2025, for its 5E Boron Americas (Fort Cady) Complex located in the Mojave Desert near Newberry Springs, California (the “Project”). A copy of the Company’s press release dated November 19, 2025 relating to the updated mineral resource estimate is furnished as Exhibit 99.1 to this Form 8-K.

The information contained in Exhibit 99.1 hereto shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference into any other filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing.

Item 8.01 Other Events.

Updated Mineral Resource Estimate

On November 15, 2025, the Company received an updated mineral resource estimate for the Project. The updated mineral resource estimate was prepared by Mr. Steven Kerr of Escalante Geological Services, LLC, one of the Qualified Persons with respect to the Company’s Preliminary Feasibility Study Technical Report Summary (the “PFS”) filed with the U.S. Securities and Exchange Commission (the “SEC”) on Form 8-K on August 7, 2025. The new mineral resource estimate updates the prior estimate dated March 10, 2025, and incorporates mineral resource from additional lode claims the Company staked and filed with the U.S. Bureau of Land Management and recorded in San Bernardino County in August 2025.

The updated mineral resource estimate identified 61.9 million short tons of measured ore, containing 9.1 million short tons of in-situ boric acid (H3BO3), with an average grade of 8.34% (B2O3), and 138.6 million short tons of indicated ore, containing 19.2 million short tons of in-situ boric acid (H3BO3), with an average grade of 7.97% (B2O3). On a combined basis, measured plus indicated mineral resource represent 28.3 million tons of boric acid, with an average grade of 8.09% (B2O3), which represents an increase of 10.8 million tons, or 61%, as compared to the prior resource estimate. The updated mineral resource estimate also identified an aggregate measured plus indicated mineral resource estimate of 328 thousand tons of lithium carbonate equivalent (“LCE”), with an average grade of 0.17% LCE, an increase of 115 thousand tons, or 54%, as compared to the prior resource estimate. Each of these increases relate exclusively to the addition of mineral resource that resulted from the aforementioned additional lode claims.

The mineral reserves and Project economics previously disclosed in the Company’s PFS are unchanged as a result of the updated mineral resource estimate and remain current and valid as of the date of this Form 8-K. Additionally, the mineral resource assumptions, methodology, pricing assumptions, cut-off grade and other assumptions and estimates with respect to the Company’s mineral resource estimate, each as described in Part I, Items 1 and 2, of the Company’s Form 10-K filed with the SEC on September 29, 2025 remain consistent and accurate as of the date of this Form 8-K.

Mineral Resource Definitions

Regulation S-K 1300 defines a “mineral resource” as a concentration or occurrence of material of economic interest in or on the Earth’s crust in such form, grade or quality, and quantity that there are reasonable prospects for economic extraction. A mineral resource is a reasonable estimate of mineralization, considering relevant factors such as cut-off grade, likely mining dimensions, location, or continuity, that, with the assumed and justifiable technical and economic conditions, is likely to, in whole or in part, become economically extractable. It is not merely an inventory of all mineralization drilled or sampled.

A “measured mineral resource” is that part of a mineral resource for which quantity and grade or quality are estimated on the basis of conclusive geological evidence and sampling. The level of geological certainty associated with a measured mineral resource is sufficient to allow a qualified person to apply modifying factors, as defined in this section, in sufficient detail to support detailed mine planning and final evaluation of the economic viability of the deposit. Because a measured mineral resource has a higher level of confidence than the level of confidence of either an indicated mineral resource or an inferred mineral resource, a measured mineral resource may be converted to a proven mineral reserve or to a probable mineral reserve.

An “indicated mineral resource” is that part of a mineral resource for which quantity and grade or quality are estimated on the basis of adequate geological evidence and sampling. The level of geological certainty associated with an indicated mineral resource is sufficient to allow a qualified person to apply modifying factors in sufficient detail to support mine planning and evaluation of the economic viability of the deposit. Because an indicated mineral resource has a lower level of confidence than the level of confidence of a measured mineral resource, an indicated mineral resource may only be converted to a probable mineral reserve.

An “inferred mineral resource” is that part of a mineral resource for which quantity and grade or quality are estimated on the basis of limited geological evidence and sampling. The level of geological uncertainty associated with an inferred mineral resource is too high

to apply relevant technical and economic factors likely to influence the prospects of economic extraction in a manner useful for evaluation of economic viability. Because an inferred mineral resource has the lowest level of geological confidence of all mineral resources, which prevents the application of the modifying factors in a manner useful for evaluation of economic viability, an inferred mineral resource considered when assessing the economic viability of a mining project must be presented along with economic viability excluding inferred resources and may not be converted to a mineral reserve.

Fort Cady Mineral Resource Estimate as of November 15, 2025

		Thick			B203			H3BO3			LCE										Resource Classification Tons										Product Tons - Measured										Product Tons - Indicated										Product Tons - Inferred
Property	Bed(1)	(m)			(%)			(%)			(%)			Tonnes			Tons				Measured			Indicated			Inferred				B2O3			H3BO3			LCE				B2O3			H3BO3			LCE				B2O3			H3BO3			LCE
	UMH		2.09			7.73			13.72			0.14			5,389,673			5,941,096				2,673,493			3,267,603		-					206,580			366,886		3729					252,486			448,416			4,557				—			—			—
Unpatented	MMH		9.26			8.99			15.97			0.20			23,883,154			26,326,663				11,846,998			14,479,665		-					1,065,024			1,891,483			23,585				1,301,696			2,311,812			28,826				—			—			—
Lode Claims	IMH		11.40			8.02			14.24			0.18			29,390,585			32,397,565				14,578,904			17,818,661		-					1,169,139			2,076,390			26,385				1,428,947			2,537,810			32,249				—			—			—
	LMH		8.38			9.02			16.02			0.12			21,607,951			23,818,683				10,718,407			13,100,275		-					966,856			1,717,136		13237					1,181,713			2,098,722			16,178				—			—			—
Sub-Total															80,271,363			88,484,007				39,817,802			48,666,204		-					3,407,599			6,051,895			66,936				4,164,842			7,396,760			81,810				—			—			—
Fee Land	UMH		2.96			6.60			11.72			0.13			5,239,482			5,775,538				1,443,885			4,216,143			115,511				95,296			169,246			1,926				278,265			494,199			5,624				7,624			13,540		154.1
	MMH		15.25			8.23			14.62			0.17			26,950,960			29,708,340				7,427,085			21,687,088			594,167				611,249			1,085,578			12,770				1,784,847			3,169,889			37,289				48,900			86,846			1,022
	IMH		6.09			7.24			12.85			0.19			10,770,455			11,872,391				2,968,098			8,666,845			237,448				214,781			381,451			5,520				627,160			1,113,837			16,119				17,182			30,516		441.6
	LMH		8.11			8.63			15.33			0.12			14,330,824			15,797,025				3,949,256			11,531,828			315,941				340,831			605,316			4,686				995,227			1,767,523			13,682				27,266			48,425		374.8
Sub-Total															57,291,720			63,153,293				15,788,323			46,101,904			1,263,066				1,262,157			2,241,592			24,902				3,685,500			6,545,448			72,714				100,973			179,327			1,992
Power Corridor	UMH		2.57			5.91			10.50			0.00			2,094,642			2,308,947				415,611			1,731,711			161,626				24,563			43,623		5.906827					102,344			181,763		24.61178					9,552			16,965		2.297
	MMH		22.06			7.83			13.91			0.15			17,965,945			19,804,059				3,564,731			14,853,044			1,386,284				279,118			495,714			5,256				1,162,993			2,065,476			21,900				108,546			192,778			2,044
	IMH		4.40			5.09			9.04			0.15			3,580,525			3,946,852				710,433			2,960,139			276,280				36,168			64,234			1,055				150,699			267,642			4,396				14,065			24,980		410.3
	LMH		4.25			7.83			13.90			0.13			3,461,337			3,815,470				686,785			2,861,603			267,083				53,754			95,466		913.9386					223,973			397,776			3,808				20,904			37,126		355.4
Sub-Total															27,102,450			29,875,328				5,377,559			22,406,496			2,091,273				393,602			699,038			7,231				1,640,010			2,912,658			30,129				153,068			271,848			2,812
Total															164,665,533			181,512,629				60,983,684			117,174,605			3,354,339				5,063,359			8,992,524			99,069				9,490,352			16,854,865			184,653				254,040			451,175			4,804
CA Surface	UMH		4.78			6.99			12.41			0.17			3,788,533			4,176,141				167,046			3,842,050			167,046				11,676			20,737		278.531					268,559			476,961			6,406				11,676			20,737		278.5
Section 36	MMH		14.02			6.76			12.01			0.20			11,109,308			12,245,912				489,836			11,266,239			489,836				33,113			58,809		980.3712					761,598			1,352,598			22,549				33,113			58,809		980.4
(Uncontrolled)	IMH		4.88			3.66			6.50			0.18			3,869,439			4,265,325				170,613			3,924,099			170,613				6,243			11,088		309.0668					143,590			255,016			7,109				6,243			11,088		309.1
	LMH		2.98			6.18			10.98			0.25			2,358,930			2,600,274				104,011			2,392,252			104,011				6,431			11,422		257.9632					147,921			262,708			5,933				6,431			11,422		258
Uncontrolled Total															21,126,210			23,287,653				931,506			21,424,641			931,506				57,464			102,056			1,826				1,321,669			2,347,283			41,996				57,464			102,056			1,826
Total															185,791,742			204,800,282				61,915,191			138,599,245			4,285,845				5,120,823			9,094,580			100,895				10,812,020			19,202,149			226,649				311,504			553,231			6,630

Table prepared using a 2.0% B2O3 cut-off grade and no lithium cut-off grade.

(1)“UMH” is Upper Mineralized Horizon, “MMH” is Major Mineralized Horizon, “IMH” is Intermediate Mineralized Horizon, and, and “LMH” is Lower Mineralized Horizon.

Forward-Looking Statements

This Current Report on Form 8-K contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended. All statements contained in this Current Report on Form 8-K that do not relate to matters of historical fact should be considered forward-looking statements, including without limitation statements regarding the Project’s mineral resource and reserve estimates and assumptions; the economic potential of the Project; our ability to establish or defend our mineral tenure; and our ability to produce boron, lithium or their related byproducts. These statements are based on management’s current assumptions and are neither promises nor guarantees, but involve known and unknown risks, uncertainties and other important factors that may cause the Company’s actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. For other important factors that could cause actual results to differ materially from the forward-looking statements in this Current Report on Form 8-K, please see the risks and uncertainties identified under the heading “Risk Factors” in our Annual Report on Form 10-K for the fiscal year ended June 30, 2025, as updated by the Company’s other filings with the SEC, including the Company’s Forms 10-Q and Forms 8-K, as well as in its filings with the Australian Securities Exchange. All forward-looking statements reflect the Company’s beliefs and assumptions only as of the date of this Current Report on Form 8-K. The Company undertakes no obligation to update forward-looking statements to reflect future events or circumstances.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

Exhibit No.		Description
99.1		Press Release dated November 19, 2025.
104		Cover Page Interactive Data File (embedded within the inline XBRL document).

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

			5E Advanced Materials, Inc.
Date:	November 19, 2025	By:	/s/ Paul Weibel
			Paul Weibel Chief Executive Officer

FAQ

What did 5E Advanced Materials (FEAM) announce regarding the Fort Cady project?

5E Advanced Materials announced an updated mineral resource estimate for its 5E Boron Americas (Fort Cady) Complex in California, effective November 15, 2025. The update significantly increases measured and indicated boric acid and lithium carbonate equivalent resources based on additional lode claims.

How much boric acid resource does FEAM now report at Fort Cady?

The updated estimate identifies 61.9 million short tons of measured ore containing 9.1 million short tons of in-situ boric acid at 8.34% B2O3 and 138.6 million short tons of indicated ore containing 19.2 million short tons of in-situ boric acid at 7.97% B2O3. Combined measured plus indicated mineral resource total 28.3 million tons of boric acid at an average grade of 8.09% B2O3.

How did the Fort Cady lithium resource change in the new estimate?

The updated mineral resource estimate reports a combined measured plus indicated lithium carbonate equivalent resource of 328 thousand tons at an average grade of 0.17% LCE. This represents an increase of 115 thousand tons, or 54%, compared to the prior resource estimate.

Did the updated mineral resource estimate change FEAM’s mineral reserves or project economics?

No. The company states that the mineral reserves and project economics previously disclosed in its Preliminary Feasibility Study remain unchanged and are current and valid as of the date of the report, despite the higher resource figures.

What drove the increase in 5E Advanced Materials’ mineral resource at Fort Cady?

The company explains that the increases in both boric acid and lithium carbonate equivalent measured plus indicated resources relate exclusively to additional mineral resource from new lode claims that were staked, filed with the U.S. Bureau of Land Management, and recorded in San Bernardino County in August 2025.

Who prepared the updated mineral resource estimate for FEAM’s Fort Cady project?

The updated mineral resource estimate was prepared by Mr. Steven Kerr of Escalante Geological Services, LLC, identified as one of the Qualified Persons for the company’s Preliminary Feasibility Study Technical Report Summary filed with the SEC.

How does FEAM define measured, indicated, and inferred mineral resources?

The company uses Regulation S-K 1300 definitions. A mineral resource is a concentration of material with reasonable prospects for economic extraction. Measured resources have the highest geological certainty, indicated resources have adequate evidence to support mine planning but lower confidence than measured, and inferred resources have limited evidence and cannot be converted to mineral reserves.