I had read about the gold rush in California but the gold rush in New Zealand was a new story for me. The reference to "colour" was also to gold which was also new to me.
We have the story of emigration and the tough life faced by all immigrants whether this took place in the 19th century or in present times. All immigrants face a period of settling in and in the rough, underpopulated areas of remote New Zealand, life was even tougher than usual. Harriet being one woman and a respectably, married one at that sets her apart from the floozies and boarding house mistresses who are the only women around.
The story is also of a marriage and its ultimate breakdown with glimpses into how people of two different temperaments who are not willing to communicate and who are really not willing to be totally free with each other, can lead to a total breakdown of the relationship.
The story is built up slowly - almost block by block. We have Harriet and Joseph and his mother Lilian coming to New Zealand with great hopes on the part of Harriet and Joseph but with a secret desire not to be part of her son's schemes on the part of Lilian who longs for the respectability and routine of what she knows. How Joseph is ensnared by the magnetic pull of gold and how he is constantly reminded of the crime he committed which forced him to leave England and Harriet in her turn thought that marriage was the only way to escape her being a permanent governess and that she looked forward to her marriage as a new beginning in her life. The failure of the marriage and the awareness of the failure by both Joseph and Harriet who kept their minds secret from each other are all part of this story.
Add to this a bit of homosexuality, Maori folk lore, descriptive countryside both bleak and luxuriant (depending on the weather!) and a good storyline and you have a very readable book.