Final answer:
The amphibole group of minerals is characterized by two parallel chains of silica tetrahedra in their structure, unlike the single chain in pyroxene minerals.
Step-by-step explanation:
The group of minerals characterized by two parallel chains of silica tetrahedra in their structure is amphibole. In silicate minerals, the silica tetrahedra, which consist of four oxygen atoms and one silicon atom, can form configurations ranging from single chains to complex frameworks. Amphibole minerals, such as hornblende, display this double-chain structure, offering distinct cleavage angles of 60 and 120 degrees, contrary to the single chain structure seen in pyroxene minerals, which have a 90-degree cleavage pattern.
The mineral group distinguished by a distinctive structure featuring two parallel chains of silica tetrahedra is known as amphibole. Silicate minerals exhibit various configurations of silica tetrahedra, ranging from single chains to intricate frameworks. Amphibole minerals, exemplified by species like hornblende, showcase the notable characteristic of a double-chain structure. This arrangement results in distinct cleavage angles of 60 and 120 degrees. This contrasts with pyroxene minerals, where a single-chain structure is prevalent, and the cleavage pattern exhibits angles of 90 degrees. The unique structural features of amphibole contribute to its physical properties, cleavage patterns, and overall mineralogical characteristics. Understanding these distinctions aids in the identification and classification of minerals within the broader context of Earth's geology and rock formations.