The Thames School of Mines is important as a wahi tapu, a place of religious instruction and, later, as the largest mining school in the country. Initially part of an urupa (burial ground) associated with Tarakonaiti pa, Pukehimana pa and Pukehinau pa, the land was gifted to the Wesleyan Church by Ngati Maru chiefs in 1868 for the construction of a place of worship in the newly-founded settlement of Grahamstown (later known as Thames). A church and a Sunday School building were soon erected, which were subsequently employed for several years. In 1885 the Wesleyans transferred the site for use as a School of Mines, expressly against the wishes of Ngati Maru, who had unsuccessfully petitioned Parliament opposing the change. In their 1877 petition, Hohepa Paraone and Hone Huiraukura stated that 'we do not desire the land to be given back but...we will never consent that the land so given shall be used for any other purpose than that for which it was given. Namely for the worship of God'.

Nevertheless opened in 1886, the new educational complex was one of about 30 schools founded nationally to stimulate growth in the goldfields with the active encouragement of William Larnach (1833-1898), Minister of Mines in the Stout-Vogel administration. Gold extraction was an important part of the economy in nineteenth-century New Zealand, providing revenue for the government as well as being a source of employment and private profit. Thames was suitable for a school of this type as the main mining centre for the Coromandel quartzfields, whose gold required extraction using advanced techniques. The institution offered practical instruction in geology, mine management, engineering and other skills to a range of high school and adult students. Women first attended in 1887, shortly after public school students were admitted to Sunday morning classes.

The School of Mines contains a number of educational and industrial structures, mostly utilitarian timber buildings erected during the late nineteenth and early twentieth centuries. Their diversity reflects different functions and the enlargement of the complex over several decades. The earliest instruction took place in the 1869 Sunday School building erected by the Wesleyan Church, which was retained on the site and converted for use as a lecture hall. A purpose-built addition in 1886 comprised an Experimental Metallurgical Works housing a two-stamp battery, roasting furnace, water wheel and tailing-pits, as well as other equipment. The battery reflected the joint 'public-private' nature of the educational venture, being employed for both teaching purposes and for crushing miners' ore as a means of gaining revenue.

Further additions to the school were carried out during the economic boom at the turn of the century, including a large mineralogical museum, opened to the public in 1901. After a period of decline, the school revived briefly when the Unemployment Board opened up disused mines for prospecting by the unemployed. The last major structures were a ball mill from the USA and a three-head stamper from the old Mahakirau battery, introduced in 1936-1937. The school closed in the 1950s, when only five Schools of Mines remained in existence, and the buildings were eventually transferred to the Thames Borough Council. The New Zealand Historic Places Trust/Pouhere Taonga purchased the buildings in 1979, and continues to maintain them and their contents as a historic property. That part of the earlier burial ground occupied by the School of Mines was registered in 2004 as Te Apuranginui wahi tapu (NZHPR Registration # 7556).

The Thames School of Mines site has great spiritual, cultural and archaeological significance as the location of an urupa and a later Wesleyan church. It is particularly important to Ngati Maru. The school complex is nationally significant as a rare and well-preserved example of its type. Only a few Schools of Mines are known to survive in New Zealand and, of these, the Thames complex was one of the most important and longest-lived. The buildings reflect important aspects of educational history, including the growing importance of technical subjects and adult education in the late nineteenth century. They are also of value for demonstrating the combination of public and private funding used for technical education before the emergence of a full state system. The buildings shed light on social and economic life in the later nineteenth and twentieth centuries, from class and gender issues to the importance of gold mining in New Zealand's economy. The complex is particularly significant for its links with science and technology, still containing a large amount of equipment related to the development of mining and extraction techniques. Its well-preserved interiors graphically demonstrate the use and appearance of educational structures prior to the twentieth century. The main lecture room is significant as a remnant of an earlier educational and religious structure. The complex is closely identified with an important part of the history of Thames, which was founded as a mining town, and enjoys public esteem as a much-visited complex of great educational value. Its importance is enhanced by being part of a well-preserved nineteenth-century urban landscape, and is associated with other nearby historic buildings, such as A. & G. Price's Foundry.