244 TJic American Geologist. April, i898 
REVIEW OE RECENT GEOLOGICAL 
LITERATURE. 
Le Gypse de Paris et les mincraux qtci T acco)iipagnent, K. Lacroix. 
(Nouvelles Archives des Museum d' Histoire Naturelle, Paris, tome 
X, 1897.) 
It is probably true, as remarked by the author, that there are few 
sedimentary regions as rich in minerals as tlie basin of Paris. It is 
equally true that there are few that have been so thoroughly searched 
and so long studied. Modern mineralogy may be said to have had its 
beginning in the Paris basin, and from the same center have gone out 
successively the great works of Rome de Lisle, Haiiy, Brongniart, 
Becquerel and Decloiseaux. The present work is no mean successor 
of the earlier parts of this series. The author denominates this his 
■'premier memoire" on this subject, and promises to follow up the 
subject, but it is difficult to conceive what further there is to be said. 
The gypsum of the Paris basin is found to lie in strata extending 
from the lower Oligocene to the Senonian of the upper Cretaceous, the 
last, however, being considered to have received it by secondary deposi- 
tion. The crystals of gypsum, which are often magnificent, reaching the 
dimension of six to eight inches, are often twinned and repeated in a 
multiplicity of ways. These forms are mineralogically described and 
often illustrated by photography on a series of elegant plates. 
The accompanying minerals, often formed by the transformation 01 
gypsum, largely by the action of pyrite and atmospheric air and water, 
are the following: pyrite, common salt, celestite, menilite, calcite, 
opal, magnesite, quartz, lutecite, chalcedony, fluoritc, apetalite, mar- 
casite, blende, websterite, melanterite, phosphorite, vivianite, siderite, 
succinite. 
Gypsum occurs not only in crystals, but as strata that have a 
thickness sometimes reaching 90 feet. From these strata it has been 
quarried for many years, furnishing the celebrated "plaster of Paris." 
One of the most interesting of the above minerals is lutecite, a form 
of quartz, lately discovered and described by Michel-Levy and Munier- 
Chalmas (Bui. Soc. Min. France, XV, 159, 1892). It is sometimes 
fibrous and sometimes in macroscopic crystals: when fibrous it differs 
from both chalcedony and quartzine in the relation the fibers bear, in 
their greatest dimension, to the axes of elasticity. In chalcedony they 
are elongated parallel to the index of elasticity np and in quartzine 
parallel to ng. In lutecite they are elongated in a direction of the 
plane ng, nm, making with ng an angle which is not yet established 
definitely but which is about 32 degrees (Wallerant). When lutecite 
appears in crystals they are short, hexagonal, doubly terminated pyra- 
mids, always united in series by their pyramidal faces or twinned by 
their bases. ?*• «• w. 
