With text all in Spanish, this information-rich book was a bit beyond my Spanish skills to adequately review it, so I handed it to one of my native-spanish-speaking second-grade teachers, who teaches a unit on rocks, and asked her to tell me what she thought.  She says she would recommend it.  Features she approved up were that it is well-organized, has an attractive layout and color photographs, uses high-academic vocabulary and appropriate grammar, highlights important vocabulary, and incorporates additional and relevant elements related to the topic.  As a librarian, I approve of the sturdy binding, and the complete range of non-fiction text features, including headings, index, glossary, charts, etc.