>mon—7/>: ms Clays of Southwest Missouri. 39 



The miners distinguish between "tallow c-lavs^ and "joint 

 clays," both of which occur associated and sometimes inter- 

 mixed in everv calamine digging in southwest Missouri, as has 

 been verified by personal examination and the reports of mining 



men. The " joint clays " are always red in color and are also 

 tougher and harsher in feel than the "tallow clay-." 



The " tallow clays " are found in layers of from several 

 inches thickness up to two and three feet, or in lumps weigh- 

 ing from 5<> to 500 lbs. above, below and intermixed with the 

 crystallized and massive calamine. When taken from the 

 ground they are generally flesh-colored, or light red and brown. 

 On drying in air the iight-colored varieties usually darken 

 becoming various shades of brown, while the dark-colored varie- 

 ties lighten becoming yellowish and sometimes ash gray. Thin 

 streaks of a pure white variety unchanged in color on air-dry- 

 ing are also found in small amounts, which are characterized 

 by a high content of zinc oxide as shown by analyses 1, 2, 3 and 

 4. appended 



The "tallow clays'' have a peculiar greasy feel ; are very 

 fine grained and perfectly plastic; on air-drying they shrink 

 and crumble into small fragments having a hardness of 1*25 to 

 15, which the miners call slacking. On moistening the air- 

 dried specimens they regain their original plasticity and in a 

 measure their original color. The air-dried specimens give off 

 water in the closed tube ; fuse on charcoal at about 3, always 

 lightening up in color, becoming white or ash gray ; give the 

 zinc coatings when heated with soda ; and are completely de- 

 composed with gelatinization when gently heated with moder- 

 ately concentrated hydrochloric acid. Their average compo- 

 sition is shown by analyses Nos. 5-20. In addition to these com- 

 plete analyses, we have made determinations of zinc oxide in 

 2< »-25 other specimens in which the least amount of zinc oxide 

 obtained was 2 1 '93 per cent and the highest 39*31 per cent. The 

 "joint clays " are usually found nearer the surface than the " tal- 

 low clays," though sometimes in close proximity to the massive 

 calamine, filling up the crevices in the latter. While they are 

 plastic they are tougher and not so fine grained as the " tallow 

 clay-." They are red in color, darken and shrink but little 

 on drying. They contain zinc oxide in amounts varying from 

 H to 14 per cent, the complete analyses 20,21 and 22 appended 

 are believed to represent their average composition. They re- 

 semble the " tallow r clays " in their behavior before the blow- 

 pipe, but are not always completely decomposed with hydro- 

 chloric acid. 



