The interplay of action and character in Spark of opal marks this as a book which has something to say to the teens; boys and girls may recognise problems of their own in its pages, even if it is unlikely that many of them will find themselves in exactly comparable situations…. With the thrills of opal-mining to dominate the plot, the growing pains of the young people and their friends provide a second theme of absorbing interest…. The author makes her points forcibly in the context of a community with its own customs and prejudices, and the background of the story is as fascinating as its events. (p. 1709)
Margery Fisher, in her Growing Point, April, 1971.
Mavis Clark explores [in Spark of Opal] several sets of relationships skilfully—within the Watson family, between the aborigines and the settlers, between the various groups of opal-mad miners. The conflicts, friendships and enmities are deftly traced and interwoven, and the unusual, lonely setting gives a lively impression of pioneer days and ways with modern trimmings. (p. 240)
The Junior Bookshelf, August, 1971.
[Iron Mountain is a] successor to The Min-Min (1969) which doesn't sag under the virtues of the first book and again surfaces with a firmly realistic contemporary story of the land down under where, in the far West, there are new worlds as well as selves to conquer…. The story is authoritatively framed and in itself has lots of grit and go-ahead momentum. (p. 1020)
Kirkus Reviews (copyright © 1971 The Kirkus Service, Inc.), September 15, 1971.