In the Chalk-rock and Chalk-marl of some parts of England glauconite is rather frequent, and glauconitic chalk is known also in the north of France.
They may be seen occupying these shells, and when the shell is dissolved away perfect casts of glauconite are set free.
Calcareous sands or impure limestones with glauconite are also by no means rare, an example being the well-known Kentish Rag.
In a small number of Tertiary and older rocks glauconite occurs as an essential component.
Apparently in some manner not understood, the decaying organic matter in the shell of the dead organism initiated or favoured the chemical reactions by which the glauconite was formed.
Films or stains ofglauconite on shells, sand grains and phosphate nodules are explained by a similar deposit of fragmental glauconite.
The green sand when weathered is brown or rusty coloured, the glauconite being oxidized to limonite.
This consists of alternations of chalk with bands of Marl, and contains glauconite and also phosphatic nodules in the lower part.
Grains of glauconite can easily be seen in a handful of sand,--better with a magnifying glass.
Glauconite is the principal, often the sole, constituent of the rock greensand, which occurs abundantly in the newer geological formations, and is now forming in the deep water of the Gulf of Mexico and along our Atlantic sea-board.
Hunt in the Report of the Survey of Canada for 1866:-- "In connection with the Eozoon it is interesting to examine more carefully into the nature of the matters which have been called glauconite or green-sand.
Thus glauconiteand even serpentine may, in a certain sense, be a sort of foraminiferal coprolitic matter or excrement.
We also find beds of glauconite retaining the forms of Foraminifera, while the calcareous tests of these have been removed, apparently by acid waters.
AB] Pourtales has followed up these investigations on the recent formation of glauconite in the Gulf Stream waters.
If we ask why this mineral glauconite should be associated with Foraminiferal shells, the answer is that they are both products of one kind of locality.
Since my attention has been directed to this subject, many illustrations have come under my notice of Silurian limestones in which the pores of fossils are infiltrated with hydrous silicates akin to glauconite and serpentine.
Similar bodies are found in the lower part of the Siluro-Cambrian, in the Quebec group at Point Levis; and there they are filled with a species of glauconite constituting a sort of greensand rock.
The green grains which are so abundant in several minor subdivisions of the Cretaceous, are also in many instances really casts in glauconite of the chambered shells of these minute organisms.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "glauconite" in a variety of sentences. We hope that you will now be able to make sentences using this word. Other words: alabaster; asphalt; color; jade; mineral; pigment
