The sample testing was done to confirm historic work and for metallurgical purposes, the company said.
Tuesday, the company reported results from 198 of 841 samples submitted for testing in a lab.
Within the underground channel sampling results, assays ranged from 15.9% total rare earth oxide (TREO) to a whopping 40.12% TREO with an average of 23.75% TREO. Forty-six underground channel samples were taken, representing 16 underground locations over a strike length of 250 metres.
Drill core assays ranged from 0.18% TREO to 31.07% TREO, with an average grade of 13.83% TREO, while surface tailings results from the first batch of 54 assays ranged from 3.85% TREO to 12.01% TREO with an average of 7.27% TREO.
When compared to historical data, the company said these results showed a higher distribution of neodymium, and the more valuable heavy rare earth oxides dysprosium and terbium. These metals are important to the company's alloy processing operations in the US and UK that produce permanent magnet alloys.
"These preliminary results are extremely encouraging for two reasons," said president and CEO Jim Engdahl.
"First, the assays reported have either matched or exceeded the historical data. Second, the comparison of Rare Earth Element (NYSEMKT:REE) distribution indicates that Neodymium, the primary REE consumed by our wholly owned subsidiary Less Common Metals, is at a higher distribution level than the historical data indicated.
"While these assay results are preliminary, we are confident that we will be able to confirm and enhance the historic information as we move toward the preparation of a National Instrument 43-101 technical report."
Great Western said the aim of the diamond drill program was to provide information in support of an NI 43-101 resource estimate for the area within the main mine site, and to collect a mini-bulk sample for metallurgical testing. The NI 43-101 compliant report for the Steenkampskraal mine is expected in the first half of this year.
The drill program was comprised of 39 holes, for a total of 3,780 metres, including 17 for resource confirmation and 22 holes dedicated to metallurgical sampling. The initial assay batch totaled 47 samples, representing eight drill holes. Highlights of drill core samples included 0.98 metres at 29.59% TREO.
Relative to the historical data, the first total batch of assays reported Tuesday indicate a distribution increase of between four and nine percent for neodymium, a rise of between 42 and 84 percent for dysprosium, and an increase of between 175 and 225 percent for terbium.
The company also said Tuesday that as a group, the heavy rare earth oxide proportion of the three types of assays, not including yttrium, showed an increase of between 29 and 59 percent over historical values.
Rare earths refer to a group of 15 specific elements, known as lanthanides, plus scandium and yttrium, used for everything from smartphones to guided missiles. While some rare earths are relatively common, they are dispersed in a way that makes it difficult to find deposits with high enough ore grades to economically exploit.
Demand for the metals is expected to continue to grow steadily as China, which produces 97 percent of the world's rare earths, has cut exports by more than half of 2004 levels to 30,000 tons in 2010.
Indeed, demand for dysprosium is expected to soar over the next decade from both the traditional automotive and emerging electric car and wind turbine industries.
Supply of the metal, which is a key contributor to high temperature magnets, has become tight over the past year, with prices increasing more than 600 percent since January 2011.
Great Western Minerals combines upstream resource exploration and extraction at its Steenkampskraal mine in South Africa with downstream metals processing facilities in the US and UK. Its specialty alloys are used in the battery, magnet and aerospace industries.
In addition to rare earth oxide analysis of the results from Steenkampskraal, the samples are also being tested for copper, gold, silver and phosphate content, with such assays pending.