Carbonatitic tear-drop lapillistone

Carbonatitic tear-drop lapilli-stone are extrusive carbonatite which is composed almost exclusively by carbonatitic spherical and tear-drop lapilli (from 0.5 to 15 mm). The lapilli-stone form a hard bank, in part due to agglutination, in part due to secondary cementation by sparrite calcite. The lapilli are pyroclastic-fall droplets of calcite carbonatite melt erupted explosively by a lava-spray to lava-fountain mechanism. The lapilli are built of micro-phenocrysts and sparse phenocrysts of calcite, which, in some case, exhibit a trachytic texture, and in some examples are vesicular. Calcite comprises > 95% of the rock, with magnetite and apatite 1-2%. Accessories include melanite, pyroxene, amphibole, biotite and titanite. The chemical composition of the Henkenberg lapilli-stone is very similar to that of alvikitic dikes and the extrusive carbonatite activity in the Kaiserstuhl is considered the surface expression of the numerous alvikitic dikes.

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Calciocarbonatite lapillistone (extrusive calciocarbonatite). From James St. John

Calciocarbonatite lapillistone (extrusive calciocarbonatite). From Tony Peterson

Calciocarbonatite lapillistone (extrusive calciocarbonatite). From Tony Peterson

Bibliography

• Ulianov, A., Müntener, O., Ulmer, P., & Pettke, T. (2007). Entrained macrocryst minerals as a key to the source region of olivine nephelinites: Humberg, Kaiserstuhl, Germany. Journal of Petrology, 48(6), 1079-1118.
• Walter, B. F., Marks, M. A. W., & Markl, G. (2016). The Kaiserstuhl natural laboratory-an introduction and first results. Abstract Malawi Expert Council.
• Weisenberger, T. B., Spürgin, S., & Lahaye, Y. (2014). Hydrothermal alteration and zeolitization of the Fohberg phonolite, Kaiserstuhl Volcanic Complex, Germany. International Journal of Earth Sciences, 103(8), 2273-2300.
• Weisenberger, T., & Spuergin, S. (2009). Zeolites in alkaline rocks of the Kaiserstuhl Volcanic Complex, SW Germany–new microprobe investigation and the relationship of zeolite mineralogy to the host rock. Geologica Belgica

Photo
Rounded carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. PPL image, 2x (Field of view = 7mm)	Rounded carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. PPL image, 2x (Field of view = 7mm)	Rounded carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. PPL image, 2x (Field of view = 7mm)
Rounded carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. PPL image, 2x (Field of view = 7mm)	Rounded carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. PPL image, 2x (Field of view = 7mm)	Rounded carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. PPL image, 2x (Field of view = 7mm)
Rounded carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. XPL image, 2x (Field of view = 7mm)	Rounded carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. PPL image, 2x (Field of view = 7mm)	Rounded carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. PPL image, 2x (Field of view = 7mm)
Rounded carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. PPL image, 2x (Field of view = 7mm)	Rounded carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. PPL image, 2x (Field of view = 7mm)	Rounded carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. XPL image, 2x (Field of view = 7mm)
Rounded carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. PPL image, 2x (Field of view = 7mm)	Rounded carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. PPL image, 2x (Field of view = 7mm)	Rounded carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. XPL image, 2x (Field of view = 7mm)
Rounded carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. PPL image, 2x (Field of view = 7mm)	Rounded carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. XPL image, 2x (Field of view = 7mm)	Tear-drop carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. PPL image, 2x (Field of view = 7mm)
Tear-drop carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. XPL image, 2x (Field of view = 7mm)	Tear-drop carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. PPL image, 2x (Field of view = 7mm)	Tear-drop carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. XPL image, 2x (Field of view = 7mm)
Rounded carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. PPL image, 2x (Field of view = 7mm)	Rounded carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. XPL image, 2x (Field of view = 7mm)	Rounded carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. PPL image, 2x (Field of view = 7mm)
Tear-drop carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. PPL image, 2x (Field of view = 7mm)	Tear-drop carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. XPL image, 2x (Field of view = 7mm)	Tear-drop carbonatitic lapilli (with calcite and magnetite phenocrysts) set in a secondary calcite groundmass. Lapillistone from Henkenberg. PPL image, 2x (Field of view = 7mm)