What is limestone?

1. What is limestone? • Limestone = a biochemical sedimentary rock made up mostly of calcium carbonate

2. How do limestones form? • Most limestones are simply the cemented remains of marine shells • Limestone “anatomy” • Grains • Skeletal particles, ooids, peloids • Lime mud • Microscopic crystals produced by calcareous algae and through abrasion of larger particles • Cement • Inorganically precipitated CaCO3 crystals

3. Skeletal grains

4. ooids

5. peloids

6. Lime mud

7. Calcite cement

8. Factors affecting precipitation of CaCO3 in sea water

9. Where do limestones form? • Because CaCO3 precipitates most readily in warm, well lit, agitated water of normal marine salinity…..most limestones form in shallow, tropical depositional environments • e.g., Bahamas, central America, Persian Gulf, NW shelf of Australia, Great Barrier Reef, Malaysia, Indonesia, etc.

10. Modern CaCO3 depositional environments *Note: Although cool water carbonates Are forming in many places, they are highly prone to dissolution and therefore do not become major limestone accumulations

11. Caicos Platform Reef tract Quiet water high-energy sand shoals Prevailing winds

12. North America during the Devonian Period

13. Iowa during the Devonian Period

14. What are limestone products? • Whole rock • Crushed limestone • Dolomitic limestone • Burned lime (calcium oxide) • High calcium lime • Dolomitic lime • Hydrated lime (calcium hydroxide)

15. How is limestone used? • Construction  • Soil stabilization • Flue Gas Desulfurization • Steel Production (flux for blast furnaces) • Glass Production • Water Treatment • Waste Treatment • Paper Production (filler) • Chemical Production • Masonry, Mortars and Other Building Materials