Description All our rocks are carefully selected for educational study. They come in labelled trays. The trays are normally 3″ x 2″ size depending on the rarity of the specimen. Average specimen size is shown below. These are ideal for classroom teaching and are a size that can be easily passed round the classroom for students to get a feel for each type. Ironstone is a sedimentary rock, either deposited directly as a ferruginous sediment or created by chemical replacement, that contains a substantial proportion of an iron compound from which iron can be smelted commercially. Approx: 30-40mm
