Half-an-hour

I yet lingered half-an-hour longer, hoping to see some sign of amity: but she gave none.

Source: tatoeba (11747965)

[S]ome very languid remarks on the probable brilliancy of the ball were all that broke, at intervals, a silence of half-an-hour, before they were joined by the master of the house.

Source: wiktionary

Alice laughed. "There's no use trying," she said: "one can't believe impossible things." / "I daresay you haven't had much practice," said the Queen. "When I was your age, I always did it for half-an-hour a day. Why, sometimes I've believed as many as six impossible things before breakfast. There goes the shawl again!"

Source: wiktionary

In about half-an-hour John and Mr. York, who was to be our new coachman, came in to see us.

Source: wiktionary