RARE ELEMENT RESOURCES LTD

Conversion Factors and Abbreviations

All units in this Annual Report are stated in metric measurements and their imperial measurement equivalents. For ease of reference, the following conversion factors are provided:

Definitions

bastnasite– a mixed lanthanide fluoro-carbonate mineral (LaCO 3 F) that currently provides the bulk of the world’s supply of the LREEs. Bastnasite and monazite are the two most common sources of cerium and other REEs. Bastnasite is found in carbonatites, carbonate rocks of igneous derivation.

beneficiation – operations that concentrate and separate mineral values in ore from waste material, and typically include, but are not limited to, crushing, grinding, washing, filtration, and leaching.

cerium (“Ce”) – a soft, silvery, ductile metallic element that easily oxidizes in air. Ce is the most abundant of the REEs and is found in a number of minerals, including monazite and bastnasite. Ce has two relatively stable oxidation states (Ce3+ and Ce4+), enabling both the storage of oxygen and its widespread use in catalytic converters. Ce is also widely used in glass polishing.

**concentrate –**a mineral beneficiation product that generally describes the material that is produced after crushing and grinding ore, effecting significant separation of gangue (waste) minerals from the desired metal and/or metallic minerals, and discarding the waste minerals. The resulting “concentrate” of minerals typically has an order of magnitude higher content of minerals than does the beginning ore material.

CREE – critical rare earth elements – Nd, Pr, Dy, and Tb were identified by the DoE as “critical” in its 2023 Critical Materials Assessment. CREEs are those projected by the DoE to have the greatest economic importance for clean energy development and the highest risk of supply disruption.

**Dy –**dysprosium (a soft metallic element of the lanthanide series, mainly used in high-performance, permanent magnets). Dy has a high melting point and absorbs neutrons well. It is therefore also used in nuclear control rods to help control nuclear reactions. Dy is also used in laser generating materials.

**Eu –**europium (a very rare metallic element that is the softest member of the lanthanide series). It is used in making color television tubes and lasers and as a neutron absorber in nuclear research. It is desirable due to its photon emission. Excitation of the Eu atom, by absorption of electrons or by UV radiation, results in changes in energy levels that create a visible emission. Almost all practical uses of Eu utilize this luminescent behavior.

fault – a surface or zone of rock fracture along which there has been displacement.

Feasibility Study (“FS”)– a comprehensive study of a mineral deposit in which all geological, engineering, legal, operating, economic, social, environmental, and other relevant factors are considered in sufficient detail that it could reasonably serve as the basis for a final decision to develop the deposit for mineral production.

FMR – Ferro-Manganese Rich – mineralization that includes iron oxide, manganese oxide and REE.

**Gd –gadolinium(**a malleable, ductile metallic element of the lanthanide series that has seven natural isotopes and 11 artificial isotopes). Two of the natural isotopes, Gd 155 and Gd 157, are the best-known neutron absorbers. Gd is used to improve the heat and corrosion resistance of iron, chromium, and various alloys in medicine as a contrast medium for magnetic resonance imaging and as a radioisotope in bone mineral analysis.

**geochemical –**related to the distribution and amounts of the chemical elements in minerals, ores, rocks, solids, water and the atmosphere.

GHG – greenhouse gases.

grade – quantity of metal per unit weight of host material.

HREEs – heavy rare earth elements – defined as the elements Tb, Dy, Ho, Er, Tm, Yb, Lu and Y.

**La –lanthanum (**the first metallic element of the lanthanide series). La is a strategically important rare earth element due to its use in fluid cracking catalysts (“FCC”), which are used in the production of transportation and aircraft fuel. La is also used in fuel cells and batteries.

**LREEs –**light rare earth elements, defined as the elements La, Ce, Pr, Nd, Pm, Sm, Eu and Gd.

mineral – a naturally occurring, inorganic crystalline material having a definite chemical composition.

mineralization – a natural accumulation or concentration of one or more minerals in rocks or soil. Also, the process by which minerals are introduced or concentrated in rocks or soil.

monazite – a reddish-brown rare earth phosphate mineral. Monazite-group minerals are typically accompanied by elevated concentrations of uranium and thorium. This has historically limited the processing of monazite. However, this mineral is becoming more attractive because it typically has elevated concentrations of HREEs.

Nd **–**neodymium (a metallic element of the lanthanide series, occurring principally in REE fluorocarbonate and monazite minerals). Nd is a key constituent of Neodymium-Iron-Boron (“NdFeB”) permanent magnets and an additive to capacitor dielectrics. NdFeB magnets maximize the power/weight ratio and are found in a large variety of motors, generators, sensors, and hard disk drives. Capacitors containing Nd are found in cellular telephones, computers and nearly all other electronic devices. A minor application of Nd is for lasers.

NdFeB – Neodymium-Iron-Boron compound used to manufacture permanent rare earth magnets.

NI 43-101 – National Instrument 43-101 – Standards of Disclosure for Mineral Projects of the Canadian Securities Administrators.

open pit – surface mining in which the ore is extracted from a pit or quarry. The geometry of the pit will vary with the characteristics of the ore body.

ore – mineral-bearing rock.

ore body – a mostly solid and fairly continuous mass of mineralization.

Ox – oxide mineralization.

OxCa – oxide carbonate.

oxide – for purposes of the deposits found at the Bear Lodge Property, rare earth bearing mineralized material that results from the complete oxidation by natural processes of sulfide-bearing material.

**PFS –**preliminary feasibility study or pre-feasibility study. Each means a comprehensive study of the viability of a mineral project that has advanced to a stage where the mining method, in the case of underground mining, or the pit configuration, in the case of an open pit, has been established and an effective method of mineral processing and/or beneficiation has been determined. It includes a financial analysis based on reasonable assumptions of technical, engineering, legal, operating, economic, social, and environmental factors and the evaluation of other relevant factors that are sufficient for a Qualified Person, acting reasonably, to determine if all or part of any mineral resource may be classified as a Mineral Reserve under NI 43-101 standards.

**Pr –**praseodymium (a metallic element that constitutes about 4% of the lanthanide content of bastnasite and has a few specific applications, based mainly on its optical properties). It is a common coloring pigment, and is used in photographic filters, airport signal lenses, and welder’s glasses. Because it chemically and magnetically is so similar to its periodic chart neighbors Nd and La, Pr is typically found in small amounts in applications where Nd and La are important, such as NdFeB magnets and catalysts. These latter applications are actually the largest uses for Pr because the magnet and catalyst markets are so large. Thus, Pr plays an important role in extending the availability of the more widely used Nd and La.

RC (reverse circulation) drilling – a rotary drilling method using either a hammer or a tri-cone bit to produce rock cuttings that are forced upward from the bottom of the drill hole to the surface through an inner tube, using liquid and/or air pressure moving downward through an outer tube.

recovery – the percentage of contained metal actually extracted from ore in the course of processing and/or beneficiating such ore.

REEs– rare earth elements. A group of metallic elements with unique chemical, catalytic, magnetic, metallurgical, and phosphorescent properties.

Sm – samarium (a metallic element of the lanthanide series predominantly used to produce Sm cobalt magnets). Although Sm cobalt magnets are slightly less powerful than NdFeB magnets at room temperature, these magnets can be used over a wider range of temperatures and are less susceptible to corrosion.

stockwork – complex system of structurally controlled or randomly oriented veins that can be standalone ore bodies or occur on the periphery of larger veins. They are also referred to as “stringer zones.”

strike – the direction or trend that a structural surface (e.g., an ore bedding or fault plane) takes as it intersects the horizontal.

sulfide – a mineral combining sulfur and base metals, such as iron and less commonly copper, lead, zinc and/or molybdenum; metallic sulfur bearing mineral associated with primary REE mineralization.

Tb– Terbium is a rare earth metal used in solid state devices as well as magnets in loudspeakers.

Technical Report – the technical report of the Company dated April 12, 2024 prepared in accordance with Canada’s NI 43-101 -* Standards of Disclosure for Mineral Projects*and titled “Technical Report on the Bear Lodge REE Project located in Crook County, Wyoming, USA” by authors Alan C. Noble of Ore Reserves Engineering, Monica Barrero Bouza of EurGeol and Jaye T. Pickarts, Consultant.

TREO – Total Rare Earth Oxide (expressed in wt.%) and consisting of the fourteen (14) individually assayed rare earth element oxides plus yttrium oxide: La2O3, Ce2O3, Pr2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, Lu2O3, and Y2O3.

TRS – the technical report summary, dated February 29, 2024, relating to the Bear Lodge REE Project prepared in compliance with Item 601(b)(96) and Subpart 1300 of Regulation S-K, which was filed as Exhibit 96.1 to the Company’s Current Report on Form 8-K filed on March 4, 2024 and is incorporated by reference in this Annual Report.

vein – a sheet like body of mineralized rock. On many properties, veins may consist largely of quartz gangue. However, on the Bear Lodge Property, veins can contain a variable assemblage that includes, but is not limited to, gangue minerals like iron and manganese oxides, quartz, calcite, clay, apatite and/or potassium feldspar with or without ore minerals.

Y – Yttrium is primarily recovered from monazite resources and is used with iron in the manufacture of microwave communication equipment.