arsenite, and the most basic, aimalolite 
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1884. | Mineralogy. 925 
the tube, fumes of arsenic on charcoal, readily melts without 
decrepitation and gives decided reactions for manganese. 
Analysis gives: 
As,O; MnO FeO MgO CaO H,O 
29.94 46.98 4.65 2.00 1.50 403 Se 100 
Formula: 2(3MnO As,O;) + 7MnO HO + 6HO 
(2) Aimatolite (Igelstrom)—At the same locality, associated — 
with the last, is a blood-red transparent mineral having the ap- 
pearance of precious garnet. It occurs always in crystals and is 
imbedded in limestone. The crystals are from one to two milli- 
trand, occur in rhombohedrons, and have a perfect basal cleavage. 
It has the same blowpipe characters as aimafibrite. 
Composition : 
As,O; MnO FeO MgO CaO H,O 
25.70 34 55 13.05 8.10 2.52 16,08 == 100 
Formula: 2(3MnO As,O;) + 8MnO HO + 6HO 
(3) Allaktite® (Sjogren).—This is another arseniate of mangan- 
ese fr ocality. It is of yellow to green color and 
occurs in flat tabular crystals, belonging to the monoclinic sys- 
tem. Crystallographically it is regarded as related to the vivian- 
ite group of minerals. It has a hardness of 4 to 5, and spec. grav. 
3.83-3.85. 
Composition : 
As,0; MnO FeO MgO CaO HO 
pn 
28.57 i 9.01 = 100.65 
3 HIS 
- Formula: 2(3MnO As,O;) + 8MnO HO + HO 
For comparison with the three formulæ here given that of a 
fourth hydro-arseniate of manganese from the same locality is 
added. The formula». of chrondroarsenite 1s 2(5MnO AsOs) 
+ 5HO. Of these four minerals the least basic 1S chrondro- 
(4) Braggerite (Blomstrand).—This mi neral is yet another from 
the same prolific locality. It is an uranium mineral allied to 
uraninite. It occurs in black crystals of the isometric system 
and in crystalline masses. The octahedron is the common form. 
Hardness 5-6; specific gravity 8.73. 
Composition : 
UO, UO, PrO ThO, CeO, Y,O; FeO CaO SiO, H,O i. 
38.82 41.25 8.41 5.64 0.35 242 1.26 9.30 0.81 0.83 pae 
(5) Colemanite (Bvans)—J. T. Evans has given S10 TEE 
1 Bull. Soc. Min. de France, vil, 1884, p. 121. 
? Geol. För. Förh. Stockholm, vil, 1884, p. 109- 
“Gen, För. Förh. Stockholm, vil, 1884, p. 59- 
Bull. Calif. Acad. Sciences, No. 1, p- 57- J 
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