Biological Minerals Formed from Strontium and Barium Sulphates. III. The Morphology and Crystallography of Strontium Sulphate Crystals from the Colonial Radiolarian, Sphaerozoum punctatum
Abstract
Sphaerozoum punctatum is a silica-skeletoned. colonial radiolarian found near the ocean surface. During reproduction the species releases celestite (SrSO_4) containing flagellated swarmers. These SrSO_4 deposits have been studied by using electron microscopy and electron diffraction. High-resolution transmission electron microscopy (HRTEM) has confirmed the single-crystal nature of each deposit. Crystal morphology is based upon an elongated square prism of {0{1}1} and {023} faces capped with {210} triangular end faces. Analysis of particles of diverse sizes suggests that crystal growth is not simple equilibrium growth'. Preferential growth along the crystallographic a axis leads to crystal elongation. The constraints leading to selective mhibition of growth along certain crystal-lographic axes through spatial or chemical effects induced by the local cellular environment are discussed.
- Publication:
-
Proceedings of the Royal Society of London Series B
- Pub Date:
- December 1989
- DOI:
- 10.1098/rspb.1989.0078
- Bibcode:
- 1989RSPSB.238..223H