How many times since has this material been ploughed up and ploughed down? Or what does the plough just keep missing? And what about land that has rarely, maybe never, been dug? As for raths, they are dotted all over the country but there are few people, even in this supposedly enlightened and skeptical age, who would disturb them, just in case ...
Finds, when they occur, are often by accident, by farming folk going about their daily lives.
I grew up near the small village of Ardagh in west Limerick, which is inextricably linked to the eighth century Ardagh Chalice, one of the country's foremost treasures, and often heard about how it was found. Along with a plainer cup and four brooches, it was unearthed in 1868 by two boys, Jim Quinn and Paddy Flanagan, digging in a potato field on the side of a ring fort at Reerasta.
Walking home from school and around the fort at home, my head swimming with visions of adventure and fame, I used to look into drains and under stones, as if there was treasure lurking everywhere.
Double ploughing, where one plough follows another to gain extra depth, led to the discovery in Derry of the Broighter Hoard, a collection of gold artefacts from the Iron Age.
The 1980 discovery of the 8th/9th century Derrynaflan hoard in Tipperary was less accidental. Michael Webb and his son, also Michael, were using to a metal detector to explore the site of an early Irish abbey.
Along with the Ardagh Chalice and the Derrynaflan Paten, the Tara Brooch is seen as the pinnacle of early medieval Irish craftsmanship.
The brooch was found by a woman in 1850, supposedly buried on the beach at Bettystown, Co Meath but some believe it may have been found inland and this was obscured to avoid a legal claim from the landowner. It was a Dublin jeweller who acquired the brooch that attributed its provenance to Tara to increase its value.
These hoards and many others are held by the National Museum of Ireland.
Some of the best known pieces are on display in Kildare Street in Dublin, many others at the fabulous Turlough House in Mayo.
Of course, the path to discovery does not always run smooth.
The National Monuments Act which was amended in 1994 in the wake of the Derrynaflan find means there is a legal obligation to report any archaeological find within three days. In a country with as long and colourful a history, further discoveries have to be likely.
A golden harvest from the bog
In 1945, a farmer named Hubert Lannon was cutting turf in Coggalbeg, Co Roscommon, when he discovered a gold lunula and two gold discs, which had lain in the bog for over 4,000 years.
Two years later, for some unknown reason, Hubert Lannon gave the artefacts to a pharmacist in Strokestown named Patrick Sheehan. Neither man recognised the significance of the find. Sheehan placed them in his family safe where they remained for over 50 years.
When the safe was stolen in 2009, the Sheehans reported the break-in and told the Gardaí that the safe contained three unusual pieces of jewellery.
They tracked down the thieves who revealed the paperwork from the safe had been dumped in a rubbish skip. Being thin, the stolen gold had been overlooked in an envelope. The skip was located and the precious hoard was miraculously recovered.