460 University Geological Survey of Kansas. 
have covellite pseudomorphous after sphalerite. It seems 
probable that a metathetic reaction has taken place between 
the zinc sulphide and copper sulphate, thus: ZnS+CuSO,= 
CuS+ZnSO,. Such areaction does take place when sphalerite 
is heated in a closed tube containing a solution of copper sul- 
phate to a temperature of 200° C., as experiments by the author 
show. Given sufficient time and favorable conditions, may 
not this reaction have taken place without the high tempera- 
ture? Associated with the covellite and exterior to it is 
malachite, which is probably a further product of the decom- 
position of the covellite. 
Galena from Cooper hollow, Galena, is often partially re- 
placed by cerussite, the unaltered galena remaining as a cor- 
roded fragment in the cavity. In these cavities covellite is 
found as an earthy, bluish-black material. Perhaps here the 
reaction PbS+CuSO,=CuS+ PbSO, has taken place. 
An average of two analyses of the pseudomorphs from the 
Big Coon mine by Mr. Edgar B. Hayes gave the results 
in column I. Calculating the Fe as FeS, Zn as ZnS, repre- 
senting the unchanged sphalerite, and deducting this and the 
SiO, and recalculating to 100 %, we have the figures in column 
II, while the theoretical for covellite is given in column III. 
I. II. III. 
SQ a ee ere te ee on clearer BA Oe ene re Os a ee 
Uisha oie rp aaa ee 2 alee 18.80 67.10 66.40 
TG aes eee en 1 bs Lae RN On en ort Vee nee 
ZN est shoo Pk CAA aE a AS SOB tal ais Aer id neon ae 
cbc Saar RL eee ar en pan 31.37 32.90 33.60 
TRO Gallstone 99.49 100.00 100.00 
Greenockite. 
Composition, cadmium sulphide, CdS; cadmium = 77-7 %, sulphur = 22-3 %; 
hardness, 3-3-5; gravity, 4-9-5; color, honey-, citron-, or orange-yellow; crys- 
tallization, hexagonal system; cleavage, a distinct, c imperfect. 
Greenockite occurs as_a thin, greenish-yellow coating on 
sphalerite. It is a very rare mineral in the district, though 
many substances are called by thatname. Some of the clays 
are incrusted with a greenish yellow material which looks 
very much like greenockite. A specimen of this kind was 
examined by Mr. Charles McClair, a member of the Survey, 
who found no cadmium whatever. The yellow coating on 
