“... The Rangitata River is one of the braided rivers that helped form the Canterbury Plains in southern New Zealand. It flows southeast for 120 kilometres from the Southern Alps, entering the Pacific Ocean 30 kilometres northeast of Timaru. The river has a catchment area of 1,773 km2 (685 sq mi) and a mean annual flow of 95 m³/s (3,400 cu ft/s) at Klondyke. The Māori name "Rangitata" (Rakitata) has been variously translated as "day of lowering clouds", "close sky", and "the side of the sky". The river formed the Rangitata Valley, in the center of the Southern Alps. Before the river enters the Canterbury Plains, part of it is diverted to the Rangitata Diversion Race for irrigation and hydroelectric generation. Towards its mouth, the river splits into two streams, forming a large delta island (Rangitata Island). As with most rivers on the Canterbury Plains its bed consists of Greywacke shingle. Agates that are found in the Rangitata River probably originate from the Mount Somers region.
Agates can be found anywhere on the Rangitata River that is east of the Mount Somers region. As with other river beds in the Canterbury region the best agate collecting conditions occur after a storm in the headwaters has pushed a large amount of water through the river. Finding agate is usually just being lucky enough to be at the right place at the right time. A wide variety of agates can be found in the Rangitata River. They can be banded, fortified, contain moss, or contain all the aforementioned characteristics at the same time. Some of the agates found are very large (25 kg or more) so one should always bring a good pack with them to carry out their finds. Colours can range from a combination of greys, blues and whites. However, agates containing other colours such as pink and black have also been found. The moss in the agates can be very dense and range in colour from very light green through to red.
Collecting in the Rangitata River can be quite taxing day as there will be a lot of walking with no guarantee of success. It takes up to two hours to drive to the Rangitata River from Christchurch. Access to the riverbed is can be gained from a number of public access points along the length of the river. However be aware that many of these are foot access only and getting to the river bed can involve quite a walk. The riverbed can be walked by anyone as long as they don’t stray on to private property adjoining the river. The beaches to the north of the Rangitata River mouth are also worth a look as good quality agates can be found on them. This is done by driving to the northern bank of the river mouth and parking it is then an easy short walk to the beach where a pleasant afternoon can be found passed by walking along the beach looking for agates. ..”
written by Scott Hardwick, Christchurch