Australia 2 1/2d Centenary of Mitchell's Exploration of Central Queensland Postage Stamp

This is a used Australian postage stamp with a denomination of 2 1/2 pence (2 1/2d). The stamp is predominantly reddish-brown in color, printed on what appears to be standard stamp paper, and features a perforated edge, though some perforations show wear and minor tears. The central design depicts a portrait of Sir Thomas Mitchell, an explorer, set within a circular frame that reads "CENTENARY OF MITCHELL'S EXPLORATION OF CENTRAL QUEENSLAND." Below the portrait, the word "POSTAGE" is clearly visible, with "AUSTRALIA" inscribed beneath it in a larger font. To the left of the portrait, there are faint depictions of sheep, suggesting the agricultural or pioneering context of the exploration. The stamp exhibits significant evidence of use, with a heavy circular postmark largely obscuring parts of the design, particularly the upper right quadrant of the circular inscription and portions of Mitchell's likeness. The postmark appears to be in a dark ink, possibly black or dark blue, making it difficult to discern any specific dates or locations within the cancellation. The paper shows signs of age and handling, including some discoloration and minor creasing or softening of the paper fibers, especially along the edges. The perforations are not uniformly intact; some are bent, and others are missing, indicating that the stamp was likely roughly removed from an envelope or sheet. The overall condition suggests a well-circulated item, consistent with its age and intended purpose. This stamp belongs to a commemorative issue and would date to the centenary of Mitchell's exploration, placing its estimated age in the 20th century. The quality of the printing, while somewhat obscured by the postmark, appears to be typical for governmental postal issues of its era.