ROSKEAR EXPLORATION DRILLING UPDATE

ROSKEAR EXPLORATION DRILLING UPDATE

1 June 2026

Cornish Metals plc (AIM: TIN) (“Cornish Metals” or the “Company”), a mineral exploration and development company focused on advancing its wholly owned and permitted South Crofty tin project (“South Crofty”) in Cornwall, United Kingdom, is pleased to provide an update on the ongoing surface diamond drilling programme in the Roskear area of the South Crofty mine.

The programme comprises approximately 2,400 metres of drilling designed to test extensions to known mineralisation and evaluate several priority exploration targets identified through historic drilling and recent geological interpretation.

Drillhole SDD26_001A has reached its final depth of 1,199.1 metres and has intersected zones of quartz-tourmaline veining with visible cassiterite, sulphide mineralisation, and alteration consistent with the target mineralised system.

Highlights

• Drillhole SDD26_001A completed to a final depth of 1,199.1 metres
• Multiple target mineralised structures intersected, including mineralised structures which host existing Mineral Resources
• Mineralised structures intercepted west of current Mineral Resource estimate (“MRE”) envelopes, highlighting potential opportunities for resource growth
• Second drillhole, SDD26_002, to commence targeting the same structures approximately 100 metres west of SDD26_001A
• Samples currently being prepared for shipment to ALS Laboratories in Loughrea, Ireland, with assay results expected in June 2026

Don Turvey, CEO of Cornish Metals commented:

“The completion of drillhole SDD26_001A marks an important milestone in this targeted exploration drilling programme at South Crofty. The drillhole has successfully intersected multiple projected mineralised structures, including extensions to known resource areas beyond the current Mineral Resource estimate envelopes.

While assay results are still pending, the visual indications of mineralisation encountered are encouraging and support our geological interpretation of continued mineralisation to the west of the existing Mineral Resource areas. This programme is designed not only to assess opportunities for future Mineral Resource growth, but also to sterilise key infrastructure areas incorporated within the current mine design. We look forward to commencing the second hole in the programme and reporting assay results in due course.”

Figure 1: Quartz chlorite tourmaline veining with visible cassiterite (e.g. orange circle) associated with tourmaline, as logged by Cornish Metals geologists.

Figure 2: Quartz tourmaline vein hosted in granite with a band of cassiterite mineralization (e.g. indicated by the orange arrows), as logged by Cornish Metals geologists.

Figure 3: Chlorite-haematite-quartz structure with disseminated cassiterite mineralisation throughout (e.g. indicated by the orange arrow), as logged by Cornish Metals geologists.

Figure 4: Chlorite alteration with visible coarse cassiterite (e.g. orange circle), as logged by Cornish Metals geologists.

Programme Objectives

• Test the western extensions of the Roskear B and Roskear South mineralised structures beyond the limits of the current Mineral Resource envelopes
• Intersect projected structures within the Roskear Numbered Zone that are not currently included in the South Crofty MRE
• Sterilise granite-hosted areas planned for critical infrastructure associated with the Preliminary Economic Assessment mine design, including planned ramp development in the Dolcoath and Roskear areas

Programme Update

The completion of drillhole SDD26_001A marks the halfway point of the two-hole, 2,400 metre drilling programme. SDD26_001A intersected along-strike interpreted projections of the Roskear 1 South, Roskear South, Roskear 6 North and Roskear 7 North structures, in addition to the target structures associated with Roskear B.

Roskear South and Roskear B contain Mineral Resources as reported in the Company’s 2023 MRE.

The Roskear 1 South, Roskear 6 North and Roskear 7 North lodes form part of a group of mineralised structures known as the Roskear Numbered Zone. These structures currently have limited supporting data from historic channel sampling and drillhole intercepts and are not presently included within the South Crofty MRE.

Following completion of SDD26_001A, the drill rig will be realigned to commence drillhole SDD26_002, which is designed to test the same structures approximately 100 metres west of SDD26_001A. Samples from SDD26_001A are currently being prepared for shipment to ALS Laboratories in Loughrea, Ireland, with assay results expected in June 2026.

Qualified Person

This news release has been reviewed and approved by Mr Stephen Holley, (BSc (Hons), ACSM, MSc, MSCM, CEng FIMMM), Technical Services Manager for Cornish Metals Inc, who is the designated QP for the Company.

ABOUT CORNISH METALS

Cornish Metals is a mineral exploration and development company that is advancing the South Crofty critical mineral project towards production. South Crofty:

• is a historical underground tin mine located in Cornwall, United Kingdom and benefits from existing mine infrastructure including multiple shafts that can be used for future operations;
• is the highest grade known tin Mineral Resource not in production with significant near-mine and regional Mineral Resource potential;
• is permitted to commence underground mining (valid to 2071), construct a new processing facility and for all necessary site infrastructure;
• is expected to produce approximately 4,700 tonnes of tin-in-concentrate annually in the first five years of full production at lowest-quartile all-in sustaining costs over an initial 14-year mine life;
• will be a low environmental impact underground mine with zero surface tailings;
• would be potentially the first primary producer of tin in Europe or North America. Tin is a Critical Mineral as defined by the UK, American, and Canadian governments as it is used in almost all electronic devices and electrical infrastructure. Approximately two-thirds of the tin mined today comes from China, Myanmar and Indonesia;
• benefits from strong local community, regional and national government support with a growing team of skilled people, local to Cornwall, and could generate over 300 direct jobs;
• is an opportunity for a secure domestic supply of tin in the UK supporting a low carbon economy.

ENDS

Engage with us directly at our investor hub. Sign up at: https://investors.cornishmetals.com/link/rLzm0y

For additional information please contact:

Cornish Metals	Fawzi Hanano Emily Allhusen	[e-mail] [e-mail]
		Tel: [phone]
SP Angel Corporate Finance LLP (Nominated Adviser)	Charlie Bouverat Adam Cowl Ewan Leggat	Tel: [phone]
Berenberg (Joint Broker)	Jennifer Lee Ivan Briechle	Tel: [phone]
Peel Hunt (Joint Broker)	Ross Allister David McKeown	Tel: [phone]
BlytheRay (Financial PR)	Tim Blythe Megan Ray Said Izagaren	[e-mail] Tel: [phone]

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