Skeletal crystals of calcite and trona from hot-spring deposits in Kenya and New Zealand
- Univ. of Alberta, Edmonton, Alberta (Canada). Dept. of Earth and Atmospheric Sciences
- Univ. of Saskatchewan, Saskatoon, Saskatchewan (Canada). Dept. of Geological Sciences
Skeletal crystals are hollow crystals that develop because their outer walls grow before their cores. The presence of skeletal crystals of calcite (three types--trigonal prisms, hexagonal prisms, and plates) and trona in hot (> 90 C) spring deposits in New Zealand (Waikite Springs and Ohaaki Pool) and Kenya (Lorusio hot springs) shows that they can form in natural sedimentary regimes. Analysis of samples from these deposits shows that this crystal morphology develops under disequilibrium conditions that are unrelated to a specific environmental or diagenetic setting. Skeletal crystals transform into solid crystals when subsequent precipitation fills their hollow cores. In some cases, this may involve precipitation of crystalline material that has a sieve-like texture. In other examples, the skeletal crystal provides a framework upon which other materials can be precipitated. Walls in the skeletal trigonal calcite prisms from Waikite Springs are formed of subcrystals that mimic the shape of the parent crystal. Similarly, plate-like skeletal crystals from Lorusio are formed of densely packed subcrystals that are < 0.5 {micro}m long. Conversely, the walls of the skeletal hexagonal calcite crystals from Ohaaki Pool and the skeletal trona crystals from Lorusio are not formed of subcrystals. Recognition of skeletal crystals is important because they represent growth that follows the reverse pattern of normal growth. Failure to recognize that crystal growth followed the skeletal motif may lead to false interpretations concerning the growth of a crystal.
- OSTI ID:
- 207881
- Journal Information:
- Journal of Sedimentary Research, Section A: Sedimentary Petrology and Processes, Journal Name: Journal of Sedimentary Research, Section A: Sedimentary Petrology and Processes Journal Issue: 1 Vol. 66; ISSN JSRAEA; ISSN 1073-130X
- Country of Publication:
- United States
- Language:
- English
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