Rare Earth Metals

Antimony refining startups selling to defense buyers need ASTM B237 Grade A metal at 99.80 percent antimony or better, with lot level assays and mine origin records for every ingot.

American Tungsten and Antimony reported on October 13, 2026 that one ingot from its Del Sol refinery in Amargosa Valley, Nevada assayed 99.8 percent antimony, while four earlier ingots assayed 99.5 to 99.6 percent. One passing sample clears the Grade A floor and shows a process change worked. It shows no repeatability, and the Defense Logistics Agency and the Army buy lots, records and continuity of supply. Financeable offtake terms include a stated minimum quantity, a price floor, an agreed assay protocol with a named umpire laboratory, and acceptance periods short enough to protect working capital.

Three domestic projects frame the supplier side: a Defense Logistics Agency contract worth up to $245 million for ingots from United States Antimony Corporation, a $2.9 billion Export Import Bank loan to Perpetua Resources for its Idaho mine, and Nova Minerals’ Alaska plant, where all key equipment arrived on October 6, 2026.

The Grade A threshold, the federal awards and the July 20, 2026 tracing order for defense contractors are established. Repeatability at Del Sol, completion of its parent’s acquisition of the site, and the price the government pays when spot prices fall are not.

Detailed Findings

What Did the Del Sol Assay Actually Show?

The Del Sol result is one 99.8 percent antimony assay on one ingot, produced after the company changed its electrowinning conditions, and it sits exactly at the ASTM B237 Grade A minimum of 99.80 percent. In its October 13, 2026 announcement the company said NSL Analytical Services of Cleveland, Ohio tested drill shavings from five ingots made from ore from the White Spar Antimony Mine in Yavapai County, Arizona. Sample 294 of the S260930 series returned 99.8 percent. Samples 290 through 293 returned 99.5 to 99.6 percent, and only the fifth ingot came from the optimized electrowinning conditions.

The laboratory measured impurities by inductively coupled plasma mass spectrometry, sulfur by pyrohydrolysis followed by ion chromatography, and mercury by cold vapor atomic absorption. It calculated antimony by difference. A by difference result equals 100 percent minus every impurity measured, so an element nobody measured counts as antimony. A buyer’s specification therefore has to name the element list as well as the antimony floor. Reporting to one decimal place also leaves no margin: a true value of 99.76 percent rounds to 99.8, so the rounding rule belongs in the contract.

Coverage of the announcement states that the 99.8 percent sample met the Grade A chemical limits for lead, arsenic, copper, nickel and iron. The coverage reviewed published no impurity values, no recovery rates, no volumes, no funding and no offtake commitment, and it records that the company’s acquisition of the entities holding Del Sol and White Spar has not completed. The company’s first ingot announcement came on September 22, 2026 and said the ingot was made without new processing infrastructure or new permitting for the current campaign. The company now says the result lets it approach the Defense Logistics Agency, Project Vault and defense primes. It also says it expects consistent output above the commercial grade, which it has not demonstrated.

On October 5, 2026 a company executive joined a delegation at White House and Office of the United States Trade Representative roundtables, where the contacts included the Trade Representative, a National Security Council official and the director of the Office of Strategic Capital. The discussion centered on funding and offtake with the federal government and defense primes. No agreement was reported.

What Grades and Impurity Limits Do Antimony Buyers Use?

Antimony ingot trades against three reference points: a 99.65 percent commercial grade, a 99.85 percent premium grade, and ASTM B237 Grade A at 99.80 percent minimum. The standard covers refined antimony as ingot, pig or cake in Grades A and B, sets limits for arsenic, sulfur, lead and other impurities, and allows any smelting or refining route, from ore or recycled feed, that meets the chemistry. Reports of the standard give Grade B a 99.50 percent minimum.

The 99.65 percent commercial grade, sold as Regulus II or Grade II, carries maximums of 0.15 percent arsenic, 0.005 percent selenium and 0.06 percent sulfur in one published trading specification. A supplier data sheet adds 0.20 percent lead, 0.002 percent copper and 0.02 percent iron for the same antimony floor. A 99.85 percent ingot assessed by a price reporting agency carries 0.05 percent maximum arsenic, 0.15 percent maximum lead and 100 parts per million maximum bismuth, and the supplier data sheet lists 0.085 percent lead, 0.001 percent copper and 0.04 percent sulfur for its 99.85 percent product.

Naming creates a trap. In that supplier data sheet Grade A means 99.65 percent antimony and Grade B means 99.85 percent, the reverse of the ASTM labels, where Grade A is the 99.80 percent product. A contract must cite the standard and its edition, never the letter alone. Physical conventions are consistent across sources: ingots of 25 to 30 kilograms, bundled or palletized near 1,000 kilograms, lots of 25 metric tons in the trading specification, and a certificate of analysis with each delivery.

The Defense Logistics Agency’s own ingot specification does not appear in the sources reviewed. The contractor describes it as stringent and gives no standard. A startup should obtain the specification attached to the stockpile solicitation and design to the stricter of that document and Grade A.

Why Do Defense Buyers Want Antimony Metal and Antimony Trisulfide?

Defense programs need antimony because ammunition consumes it and because foreign producers control most