-~ 
1885.] Mineralogy and Petrography. i 299 
and shows that its physical properties are those of pyroxene! An 
optical examination of a series of carefully analyzed natural 
pyroxenes also yielded Doelter interesting results regarding the 
particular constituents which caused an increase in the size of the 
extinction angle on the clinopinacoid? Wiik? attributed this to 
the amount of FeO present (vid. NATURALIST, Oct., 1882, p. 836), 
but Doelter considers it rather dependent on the proportions of 
the molecules Fe Ca SiO; or R R, SiO, which the pyroxene 
contains, in this following the suggestion recently made by Fr. 
Herwig in his article on the optical orientation of the pyroxene- 
hornblende minerals. 
In this connection may be mentioned among the synthetical 
work lately produced in France, the artificial production of rho- 
donite, tephroite, hausmanite, barite, celestite and anhydrite by 
Alex. Gorgeu ;> that of apatite and wagnerite containing Br in 
place of Cl by A. Ditte; and that of albite, orthoclase and anal- 
cite in the wet way by Friedel and Sarasin.’ : 
The reprint in book form of L. Bourgeois’ article on the arti- 
ficial reproduction of minerals, written for the Encyclopédie 
chimique,’ is, notwithstanding Fouqué and Lévy’s recent and 
very complete work on the same subject, a very valuable addition 
to the literature of this most interesting line of research. 
Boron Minerats—Rammelsberg® has recently published the 
results of his new examination of the natural borates, which he 
arranges, starting with the metaboracic acid R, B O; as the nor- 
mal, as follows 
Priceite (pandermite) Ca, B Os + 5aq = {2a p o} + 4q 
Boracite (stassfurtite) 2Mg, B, O,,-+ MgCl, = 2 { 3M8 id of} +. MgCl, 
oiy Ce BO C ENO 
Hydroboracite { ar eiL E Izag = H HB o} + 5aq 
Mg, Bs Oy 
‘ ; Na, Be On + 4 of aNa BO i 
Boronatrocalcite (ulexite) { 2(Cay By On anes Tey ee BO, T 
2{ B ot} + 19 
? Na, B, O 8aq)} _. { 2Na BO,) Ca B, O, 
Franklanaite {73+ pt ou E gad} = {°H Bor} + {a Bros} + 74 
Borax (tinkal) Na, B, O; + 10aq = af BO} + 994 
? Neues Jahrbuch fiir Min., etc., 1884, 11, pp. 51-66. 
3 ib., 1885, 1, pp. 43-68. 
* Zeitschrift für Krystallographie, VIII, p. 208. 
* Schulprogramm des Kgl. Gymnasium, Saarbrücken, 1884, pp. 175. 
Š Comptes rendus, 1883, XCVII, p. 320, ib., XCVI, pp. 1144 and 1734- 
Comptes rendus, 1883, XCVI, pp. 575 and 846. 
T Comptes rendus, 1883, XCVII, p. 290. 
$ Paris, 1884, 8vo, pp. 228, viir planches, Dunod éd. 
° Neues Jahrbuch für Min., etc., 1884, I, 158-163. 
