• A new geophysical model at DTR’s Colosseum project has identified a dense circular feature, similar to the geophysical feature at the Mountain Pass rare earth mine
  • The model fits the hypothesis that Colosseum contains a circular carbonatite body
  • DTR has designed a plan to target the potential carbonatite in areas containing REE bearing fenites in the first instance


A new geophysical model for the Colosseum project has identified a circular carbonatite body, much like the geophysical feature at one of the world’s highest grade rare earths (REE) mines, Mountain Pass.

Dateline Resources’ (ASX:DTR) Colosseum gold mine, at the southern section of the Walker Lane trend in East San Bernardino Country, California, USA boasts a 20.9Mt resource grading 1.2 g/t gold for 813,000oz.

The Walker Lane Trend is host to several substantial discoveries including the Corvus Gold 1.7Moz Mother Lode deposit and the 6.5Moz Castle Mountain gold mine owned by Equinox Gold.

The company acquired the historic project from Barrick Gold in 2021, which produced roughly 344,000oz of gold between 1988 and 1993 from a historically calculated mining reserve of 700,000oz.


REE prospectivity

As well as gold, DTR’s Colosseum acreage is also highly prospective for REEs following the discovery of notable concentrations in initial samples last year.

The explorer’s experts confirmed that rock units surrounding the breccia pipes at Colosseum are genetically related to the nearby Mountain Pass mine, the highest-grade rare earth mine globally.

Recent geophysical modelling for the project has indicated a high relative density area (postulated carbonatite body) around these breccia pipes, which again, boast similarities to Mountain Pass, only 10km to the southeast.

One of the mapped fenite dykes was exposed along the eastern wall of the south mine pit, further accentuating the proximity of alkalic-carbonatitic related rock in the area surrounding the rhyolite breccia pipes.


Drill program designed to test northern side of pit

“Our rare earth experts have been adamant that we are in the right area for the discovery of a rare earth orebody, with many of the observed features being similar to that observed at the large Mountain Pass mine to the southeast,” DTR managing director Stephen Baghdadi says.

“Drill planning was somewhat hampered by the ‘noise’ that the waste dumps, stockpiles and tailings dam produce – this new model cuts through the noise to give a higher resolution view of density and demonstrates greater continuity of the high-density body.

“The model fits the hypothesis that Colosseum contains a circular carbonatite body may have been intruded by the later gold-bearing breccia.”

Baghdadi says Dateline will be targeting the preserved margins of the postulated carbonatite in areas where there is rare earth bearing fenites, a strong indicator for carbonatite related rare earth mineralisation.

“We have a drill rig on site at Colosseum and we will look to commence the rare earth program later in the year, subject to funding from the current entitlement issue.”

Based on the modelling, Dateline has developed a conceptual drilling plan for rare earths at Colosseum, initially targeting the northern side of the historic pits where rare earth’s bearing fenites have been mapped in outcrop.



This article was developed in collaboration with Dateline Resources, a Stockhead advertiser at the time of publishing.


This article does not constitute financial product advice. You should consider obtaining independent advice before making any financial decisions.