HYDROUS SILICATES—MARGAROPHYLLITE SECTION. 3807 
Greece, Moravia, Spain, ete. ; also in fibrous scams at a sil- 
yer mine in Utah. 
Aphrodite. Similar to the preceding. MgO;:Si+7H. From Swe- 
den. Cimolite, a clay from the Island of Argentiera, Kimole of the 
Greeks. Smectite, a kind of ‘‘ Fuller’s Earth,” a name given to unc- 
tuous clays used in fulling cloth. Montmorillonite, Stolpenite, and 
Steargillite, are related clay-like minerals. 
Glauconite.—Green Earth. 
In dark olive-green to yellowish-green grains, or granular 
masses, with dull lustre. H.=2. | Gi=2°2-2-4. 
Composition. Essentially a silicate of iron and potassium. 
Formula RR O,.Si,, in which R is mainly Fe and K, with 
sometimes Me; and&is Al, but sometimes largely Fe. Analy- 
ses give mostly 50-98 per cent. silica, 20-24 iron protoxide, 
4-12 of potash and 8-12 of water. B.B. fuses easily to a 
magnetic glass. Yields water in a closed tube. 
Obs. In a more or less pure state it forms thick beds in 
the Cretaceous formation, and also in the Lower Tertiary 
of New Jersey ; also occurs in other older rock formations 
down to the Lower Silurian. Found also, ffrst by Pour- 
tales, in the pores of corals and cavities of Rhizopod shells 
over the existing sea-bottom, showing it to be a marine 
product, and one now in progress of formation. The grains 
of the Cretaceous, Tertiary, and Lower Silurian beds have 
been shown by Ehrenberg to be the casts of the interior of 
shells of Rhizopods. ‘The silica has been supposed to come 
from the siliceous secretions of a minute sponge growing in 
the cavities that afterwards became occupied by the glau- 
conite. 
Celadonite. A green earth with 53 per cent. of silica, from amygda- 
loid, near Verona. Probably an impure chlorite. 
Chloropal. A massive greenish-yellow to pistachio-green compact 
mineral, somewhat opal-like in appearance, consisting chiefly of silica, 
iron sesquioxide, and water. ontronite, Pinguite, Unghwarite and 
Gramenite are varieties of it. 
Stilpnomelane. Foliated and also fibrous, or as a velvety coating. 
Black to brownish and yellowish bronze in color and lustre. G.= 
o-3°4. Chiefly silica and iron oxides, with 8 to 9 per cent. of water. 
Chalcodite of the Sterling Iron Mine, Antwerp, Jefferson County, 
N. Y., is here included. 
Serpentine. 
Usually massive and compact in texture, of a dark oil- 
green, olive-green, or blackish-green color ; also pale yel- 
