Rio De Oro (ASX: RDO) - IPO Review of a Copper and Gold Explorer in Argentina

2 days ago

10 min read

The Rio De Oro IPO offers up to 75 million shares at A$0.40 to raise A$20 million to A$30 million. Most of the money goes to drilling Nivaldo, a copper target less than 4 km from the Josemaría deposit in Argentina’s Vicuña district. The offer closes on 6 November 2026 and trading is due to start on 30 November 2026.

Rio De Oro Corp Ltd (ASX: RDO) IPO, copper and gold exploration in Argentina. Samso News.

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Rio De Oro Corp Ltd (proposed ASX: RDO) is raising A$20 million to A$30 million at A$0.40 a share, and the offer closes on 6 November 2026 [R1]. We are looking at it because copper is close to its two-year high and this copper float is next door to one of South America’s largest copper developments. Its main project, Nivaldo, sits less than 4 km north of Josemaría, one of the deposits in the Vicuña district on the Chile and Argentina border. This is Samso’s first piece on it.

Copper and gold prices in this piece are weekly closes for the week ending 23 October 2026.

THE SOURCE DOCUMENT

Rio De Oro Corp Ltd, Replacement Prospectus dated 22 October 2026. It replaces the prospectus dated 15 October 2026, adding risk wording to the Chairman’s letter and making clear that drilling at Pedernales needs environmental approvals first. It runs to 361 pages, including an Independent Geologist’s Report (IGR) by LPF Consulting and a legal report on the Argentine tenements. It is available from the Rio De Oro website.

The Rio De Oro IPO Offer

The offer is for 50 million to 75 million new shares at A$0.40 (TABLE 01). It is not underwritten, so no broker has agreed to take up any shortfall. Bell Potter and Canaccord Genuity are the joint lead managers, the brokers that run the offer. Moxico Resources plc, already a 19.99 per cent holder, has agreed to subscribe for at least enough shares to stay at about that level, or A$6 million worth if that is less. That is about A$4 million at the minimum raise and A$6 million at the maximum [R1].

TABLE 01. The Rio De Oro IPO at a glance. The dates are the indicative timetable and the company can change them. Columns: Item, Minimum subscription, Maximum subscription. Shares offered at A$0.40: Minimum subscription 50,000,000, Maximum subscription 75,000,000. Amount raised before costs: Minimum subscription A$20,000,000, Maximum subscription A$30,000,000. Shares on issue at listing: Minimum subscription 157,587,270, Maximum subscription 182,587,270. Market capitalisation at A$0.40: Minimum subscription A$63,034,908, Maximum subscription A$73,034,908. Pro forma cash, 30 June 2026: Minimum subscription A$18,985,197, Maximum subscription A$28,346,377. Shares expected to be escrowed 24 months: Minimum subscription 59,194,522 (37.56%), Maximum subscription 59,194,522 (32.42%). Shares free to trade at listing: Minimum subscription About 62%, Maximum subscription About 68%. Underwritten: Minimum subscription No, Maximum subscription No. Joint lead managers: Minimum subscription Bell Potter, Canaccord Genuity, Maximum subscription . Offer closes: Minimum subscription 6 November 2026, Maximum subscription . Expected first day of ASX trading: Minimum subscription 30 November 2026, Maximum subscription . Source: Rio De Oro Corp Ltd replacement prospectus dated 22 October 2026, Key Offer Information, sections 1.8, 2.1, 2.5 and 9.5. Free-to-trade shares are Samso arithmetic from the escrow estimate in section 10.5 (PDF page 106). The prospectus gives a free float of 62% to 67%.

At A$0.40 the company is worth A$63.0 million to A$73.0 million. Take away the pro forma cash and, by Samso’s arithmetic, both ends of the range put about A$44 million to A$45 million on the projects and the company. Pro forma means the balance sheet as if the offer had already happened. About 59.2 million shares are expected to be escrowed for 24 months, which means their holders cannot sell. That leaves about 62 to 68 per cent of the shares free to trade from the first day [R1].

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Three Projects in Argentina

FIG. 01. Map of Argentina showing the three Rio De Oro projects: Nivaldo (copper and molybdenum) in La Rioja, Pedernales (gold and silver) in Catamarca to the north, and Somuncura (gold and silver) in Río Negro in the south.

Nivaldo is in La Rioja province, more than 4,000 m up in the Andes. It is a porphyry copper target. A porphyry deposit is a large, low-grade body of copper formed around a buried intrusion of molten rock, and most of the world’s copper comes from them. Pedernales in Catamarca and Somuncura in Río Negro are epithermal gold targets. Epithermal deposits form from hot water near the surface and can carry high gold and silver grades in veins (TABLE 02) [R1][R2].

TABLE 02. The three projects and the drilling the IGR plans over two years. Nivaldo carries most of the money and most of the metres. Columns: Project, Province, Target, Area, Planned metres, min / max. Nivaldo: Province La Rioja, Target Porphyry copper-molybdenum, Area 1,100 ha, one mine concession, Planned metres, min / max 5,500 / 10,400. Pedernales: Province Catamarca, Target High-sulphidation gold, Area 39,546 ha, nine tenements, Planned metres, min / max 2,000 / 2,000. Somuncura: Province Río Negro, Target Low-sulphidation gold-silver, Area 46,385 ha, 13 tenements, Planned metres, min / max None / 2,000. Total: Province , Target , Area , Planned metres, min / max 7,500 / 14,400. Source: Rio De Oro Corp Ltd replacement prospectus dated 22 October 2026, sections 1.8 and 3. Planned metres from the Independent Geologist’s Report by LPF Consulting in the Rio De Oro Corp Ltd replacement prospectus dated 22 October 2026.

Nivaldo is the reason for the float. The Vicuña district holds Josemaría and Filo del Sol, owned by a BHP and Lundin Mining joint venture (FIG. 02). Nivaldo still has to show a deposit of its own, and the rocks are the right age for one. Rhenium-osmium dating of molybdenite, a molybdenum mineral, at Nivaldo gave 24.6 million years, close to the 25 to 24.5 million years published for Josemaría [R2].

What the First Nivaldo Drilling Found

Rio De Oro drilled nine diamond holes for 3,564 m at Nivaldo between December 2024 and May 2025, at a cost of about US$3.7 million [R2]. Diamond drilling cuts a solid core of rock. The holes hit long runs of low-grade copper and shallow zones of chalcocite, a copper mineral that forms when weathering concentrates copper near the surface (TABLE 03, FIG. 03).

TABLE 03. Selected results from Rio De Oro’s own 2025 diamond drilling. Lengths are downhole and true widths are not known. Grades at Nivaldo are copper, at Caltrauna (Somuncura) gold. Columns: Hole, From (m), Interval (m), Grade, Comment. NVDD01: From (m) 0, Interval (m) 54, Grade 0.25% Cu, Comment Includes 27 m at 0.42% Cu from 9 m, chalcocite. NVDD02: From (m) 18, Interval (m) 55, Grade 0.23% Cu, Comment Includes 22 m at 0.35% Cu from 20 m. NVDD02: From (m) 131, Interval (m) 166, Grade 0.13% Cu, Comment . NVDD02: From (m) 323, Interval (m) 63, Grade 0.15% Cu, Comment IGR: ends in mineralisation. NVDD03: From (m) 96, Interval (m) 334.9, Grade 0.17% Cu, Comment Includes 42 m at 0.26% and 22 m at 0.43% Cu. NVDD06, NVDD09: From (m) , Interval (m) , Grade No significant intercept, Comment . CADD02 (Somuncura): From (m) 43, Interval (m) 65.5, Grade 0.48 g/t Au, Comment Includes 25.5 m at 1.08 g/t Au from 83 m. Source: Independent Geologist’s Report by LPF Consulting in the Rio De Oro Corp Ltd replacement prospectus dated 22 October 2026, Table 2.4 (PDF page 153) and section 4.2.3 (PDF page 188). Intervals at a 0.10% copper cut-off at Nivaldo.

FIG. 03. Oblique three-dimensional view of drill holes NVDD01, NVDD02 and NVDD03 at Nivaldo Central with labelled copper intercepts, including 29 m at 0.40% copper, 22 m at 0.35% copper, 368 m at 0.14% copper, 334 m at 0.17% copper and 42 m at 0.26% copper. Arrows mark the system as open to the west and at depth. Josemaría is labelled 3.5 km away.

The holes found copper over long runs, at low grades. In our reading, 334.9 m at 0.17 per cent copper in NVDD03 describes the edge of a system rather than its centre. The IGR says none of the holes reached the intrusion thought to have produced the copper [R2]. In June 2025 Dr Richard Sillitoe, a porphyry specialist, reviewed the core. He recommended drilling further west, where he saw signs that grades may improve [R2]. The planned holes start about 800 m west of the 2025 drilling (FIG. 04).

FIG. 04. Conceptual cross-section at Nivaldo showing hole NVD2 in the porphyry halo near surface, an interpreted porphyry core at depth, and a proposed drill hole aimed at the core.

Two parts of the prospectus report NVDD02 differently. The company overview in section 3 gives one interval of 368 m at 0.14 per cent copper from 18 m. The IGR’s Table 2.4 splits it into three intervals between 18 m and 386 m, with gaps where the grade fell below its 0.10 per cent cut-off [R1][R2]. Both are quoted here as published. The IGR describes Nivaldo as environmentally permitted and ready to drill. It lies within the Laguna Brava Ramsar site, a protected wetland reserve, though not on the wetland itself, and in an area covered by Argentina’s Glacier Law, so its work carries conditions [R1][R2][R3].

Pedernales and Somuncura

Pedernales lies 65 km from the Salares Norte gold mine in Chile. Newcrest drilled ten holes at Vallecito in 2016 to 2018 without significant results. Rio De Oro plans about 2,000 m in the second year, aimed deeper than about 250 m below surface [R2].

The prospectus is not consistent on whether Pedernales can be drilled now. The risk section and the legal report say its environmental approval has expired and must be updated before drilling [R1][R3]. The JORC table in the IGR says the approvals “currently cover the planned exploration activities” [R2]. Samso reads the risk section and the replacement prospectus’s own change of wording as the more recent position.

At Somuncura, CADD02, drilled in late 2025 beside an older hole to check its grades, returned 65.5 m at 0.48 g/t gold from 43 m [R2]. Grams per tonne, or g/t, is the weight of gold in each tonne of rock. Rock chips at El Bagual returned up to 33 g/t gold, but no hole has been drilled there [R1].

Use of Funds from the RDO IPO

About 77 to 80 per cent of the money goes to exploration (FIG. 05). Nivaldo gets A$9.87 million at the minimum and A$17.6 million at the maximum, enough for 5,500 m or 10,400 m of drilling [R1][R2]. The first 3,564 m cost about US$3.7 million, so the 5,500 m planned at the minimum is about one and a half times the 2025 program.

FIG. 05. Bar chart of Rio De Oro’s use of funds. Minimum subscription, A$20.05 million: Nivaldo A$9.87 million, Pedernales A$4.37 million, Somuncura A$0.97 million, other tenements A$0.20 million, costs of the offer A$1.52 million, corporate overheads A$2.80 million, working capital A$0.32 million. Maximum subscription, A$30.05 million: Nivaldo A$17.6 million, Pedernales A$3.86 million, Somuncura A$2.4 million, other tenements A$0.20 million, costs of the offer A$2.11 million, corporate overheads A$2.40 million, working capital A$1.40 million.

The prospectus gives the costs of the offer two ways. Section 1.8 says about A$2.3 million to A$2.9 million. Section 10.10 says A$2,179,295 to A$2,762,755, of which A$1.52 million to A$2.11 million is paid from the money raised [R1]. Either way, about A$1.5 million to A$2.1 million of the raise goes on the offer itself. Rio De Oro had A$999,125 of cash at 30 June 2026 and a US$200,000 loan facility to bridge it to listing [R1].

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Copper and Gold Prices

COMEX copper closed the week to 23 October 2026 at about US$6.48 a pound, up about 27 per cent in a year. Gold closed at about US$4,008 an ounce, or about A$5,710. That is about 3 per cent lower than a year ago and down from about US$5,248 in February 2026, but still about 45 per cent above October 2024 (FIG. 06) [R4]. Prices move daily. For an explorer, prices matter through investor appetite and what a discovery could be worth.

Board, Shareholders and Escrow

“Investment in mineral exploration involves risk.” Richard Monti, Chairman, in his letter to investors in the replacement prospectus dated 22 October 2026 [R1]

Richard Monti chairs the board, Corey Nolan is Managing Director and Gustavo Rodriguez is Technical Director. Two of the five directors are independent. Bernard Rowe is also a director of Moxico [R1].

The founders hold most of the company. Vallecito Mining Pty Ltd owns 35 million shares, and Enrique Martin’s family owns 40 per cent of it, with Mr Rodriguez and Carlos Saravia-Frías holding 30 per cent each. By Samso’s arithmetic, Vallecito, the founders’ direct holdings, Mr Martin’s other company and Moxico together hold about 44 to 48 per cent of the shares at listing [R1]. There are also 7 million existing options, exercisable at a 50 per cent premium to the offer price and expiring three years after listing [R1].

The auditor, BDO, gave an unmodified opinion with an emphasis of matter on going concern, which means the company’s ability to keep paying its bills depends on this raise [R1].

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What Comes Next for Rio De Oro

The close of the offer on 6 November 2026, and where the raise lands between A$20 million and A$30 million.
A geophysical survey at Nivaldo and the first deep holes aimed west, towards the interpreted porphyry core.
An updated environmental approval at Pedernales, which the company needs before it drills there.
Results from Somuncura, if the raise reaches the level that funds drilling there.

Samso Concluding Comments

Rio De Oro has drilled, dated and reviewed Nivaldo. It has not yet found the centre of the system, and that is what the IPO money is for. For readers comparing copper floats, our reviews of the Lux Copper IPO and the Jacaranda Natural Resources IPO cover two others, and our Capability X IPO review is the most recent in the series.

SAMSO TAKE

We like the address and the plain drilling story. The company says its holes hit the edge of the system and explains why it is drilling west.

The offer price pays for that idea. About A$44 million of the value at A$0.40 sits on the projects rather than in the bank, ahead of the holes that test the core. A few deep holes at Nivaldo will do most of the work of setting the value. Will the first deep holes to the west find the core?

THE OTHER WAY TO READ THIS

On the favourable side, the money is aimed at a defined target with a stated reason, in one of the better-known copper districts in South America. The rock age matches its neighbour, and a strategic holder, Moxico, is putting in more money at the offer price.

On the other side, the grades drilled so far are low, the intrusion has not been found, and Nivaldo sits inside a protected Ramsar reserve and a Glacier Law area. The offer is not underwritten, the auditor flags going concern, and about two-thirds of the shares can trade on the first day.

VOCABULARY, IN PLAIN ENGLISH

Porphyry copper deposit

A large, low-grade copper deposit formed around a buried intrusion of molten rock. Most of the world’s copper comes from these.

High- and low-sulphidation

Two classes of epithermal system, named for the chemistry of the fluids that formed them.

Epithermal deposit

A gold and silver deposit formed by hot water close to the surface, often in veins.

Chalcocite

A copper mineral that can form near the surface when weathering concentrates copper.

Diamond drilling

Drilling that cuts a solid core of rock, the most reliable sample an explorer can take.

Downhole length

The length of an interval along the hole. It is not the true width of the mineralised zone.

Cut-off grade

The lowest grade counted when an interval is reported.

g/t

Grams per tonne, the weight of gold in each tonne of rock.

Independent Geologist’s Report (IGR)

A technical report on the projects written by geologists who are independent of the company.

Pro forma

Accounts shown as if a planned event, here the offer, had already happened.

Escrow

A period in which a holder cannot sell.

Underwritten

An offer where a broker has agreed to buy any shares investors do not take.

Going concern

The assumption that a company can keep paying its bills as they fall due.

Market capitalisation

The number of shares on issue multiplied by the share price.

References and sources

Every company figure in this piece comes from the prospectus unless another source is named. Where two parts of the prospectus disagree, both figures are quoted as published.

[R1] Rio De Oro Corp Ltd, Replacement Prospectus dated 22 October 2026. It replaces the prospectus dated 15 October 2026. Available from the company website. https://riodeoro.com.au/prospectus/

[R2] LPF Consulting S.R.L. (Diego Charchaflié), Independent Geologist’s Report on the Argentine Mineral Assets of Rio De Oro Corp Ltd, effective date 29 September 2026, in the replacement prospectus dated 22 October 2026.

[R3] Argentinian Legal Report on Tenements, in the Rio De Oro Corp Ltd replacement prospectus dated 22 October 2026.

[R4] Yahoo Finance, weekly closes of COMEX copper (HG=F) and gold (GC=F) futures, read 26 October 2026. https://finance.yahoo.com

Cover image: Andean landscape from the cover of the Independent Geologist’s Report by LPF Consulting, in the Rio De Oro Corp Ltd replacement prospectus dated 22 October 2026 (PDF page 124).

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