These sources were in due course depleted or became uneconomic.

Clearly the smaller mills were becoming uneconomic.

The smelter closed in September 2003, since it had become uneconomic.

The open pit is becoming gradually uneconomic and it was estimated that mining would slow down and stop by 2020.

One of the key reasons given was the failure to notice that sugar production had become dramatically uneconomic.

In the 1960s the line became uneconomic and was closed in 1969.

By then importing gas into Australia had become uneconomic.

However, by the mid-1960s, shipbuilding on the Clyde was becoming increasingly uneconomic and potentially faced collapse.

As a result the work has become uneconomic for many and they have ceased doing it.

Now oil has also become uneconomic, forcing N. Ireland's gas undertakings to close.