9 



TAB. CVL 



FERRUM argillaceum. 

 Argillaceous Oxide of Iron. 



Class 3. Metals. Order 2. Mixed. 

 Gen. l. Iron. Spec. 1. Argillaceous. 



Div. 1. Imitative. 



These seem common in marly and gravelly land, and are 

 abundant at Shotoverhill and its neighbourhood, where they 

 are situated so as to assist in forming the fine yellow ochre 

 of so great value as a pigment. They vary extremely in their 

 shape, sometimes branching like a stag's horn, or a branch 

 of a tree, and have been taken for such petrified. They are 

 often coated concentrically, imitating, as it were, the Me- 

 dulla, Liber, Cortex and Cuticle. It may seem that the mois- 

 ture in passing through loosish marl has been impregnated 

 with the oxide of iron, and, periodically drying, leaves the 

 marl and oxide of iron concentrated ; which forms the coat- 

 ing, according to the looseness of the earth. They some- 

 times concentrate to a ball, but at other times have only one 

 or two coatings. 



The upper figure is from Charlton in Kent, and had the 

 remains of a shell of the Turbo kind in it. The inside of the 

 screw is covered with minute crystals of carbonate of lime : 

 ial. 62. 63. There are other impressions of shells about it. 



The left-hand figure has the form of a pebble with a 

 lightish ferruginous ochre on the inside_, and a dark crust. 



