Agates have been found all along the shores of the Tay estuary between Tentsmuir in the east and towards Newburgh, eighteen miles to the west, with particularly fruitful locations at Tayport and Balmerino. Examples from these locations vary markedly and many different types are found. Tentsmuir Sands fronts a substantial area of nature reserve and forest and seals frequent the less accessible and quieter parts of the extensive local beaches. Although the latter are mainly composed of sand, the occasional patches of shingle have provided ‘discoid and ovoidal agates, many of them white with exposure on the sea beach. It seems very likely that the origin of these stones is from undersea sources where the Tay crosses amygdaloidal andesitic rock between Tayport and Dundee. Tentsmuir fronts the North Sea coast and when the winds blow from the east new material is cast up on a regular basis. Although finds are relatively sparse, careful searching can provide some pleasant surprises.

Further west, after rounding Tentsmuir Point, at Tayport, ‘large blocks of carnelian agate were uncovered during excavations for the Tay Railway Bridge in the 1880s’ The bedrock here comprises a continuation of the andesitic lava on the opposite side of the estuary and outcrops along the shoreline. However, the relatively benign tidal scour along the estuarial coast, leads to only small amounts of new material being cast up on the local beaches.

As a result the chances of quality finds have tended to diminish over the years, although perseverance and a willingness to use a heavy hammer and chisel can still lead to substantial success for the dedicated collector. Tayport stones occur in a wide variety and in the past, very small quantities of a rare form of plume agate have also been found. Continuing west and passing previously productive locations at Wormit Bay  the traveller arrives at the old established settlement of Balmerino, site of a thirteenth century Cistercian Abbey and now a popular local picnic destination. It has been a productive source over the years, although today rather overexploited.  

Balmerino is famous for generally small but highly detailed fortification and eye agates. The former frequently include stones with highly lamellated and intricate patterns. The slopes of nearby Scurr Hill also produce a wide variety of types as well as some of the best moss agate found in Scotland. In the nineteenth century this was a popular collecting site but woodland now covers much of the hill. However, farmland to the south also produces many examples of coloured agates.

The extensive series of beaches continue to the west but further up the estuary the Tay begins to shallow and the long reaches of shingle found nearer the open sea begin to be replaced by extensive mud flats unsuitable for beach excursions. Farmland, rising steeply along the southern banks of the river at this point, and comprising outliers of the Ochil Hills towards Newburgh, provides new possibilities for finds however.