Physical characters
The properties of glaucochroite as determined by Penfield are as follows: Basal cleavage very poor, hardness 6, specific gravity 3.407, luster vitreous, color delicate bluish green and of small crystals white or pinkish. It is optically negative, the axial plane being parallel to the base. Bx_a = [perpendicular to] (010); r > v (marked); 2V over X = 60° 51' ; a = 1.686, b = 1.722, g = 1.735, g – a = 0.049.

Composition
Glaucochroite is a calcium manganese orthosilicate, analogous to tephroite, calcium taking the place of half the manganese.

[Analyses of glaucochroite]

The first analysis gives excellent molecular ratios for the formula CaMnSiO₄. The third is closely similar, the zinc being known to be present in willemite. The second analysis is of dull-gray, very fine grained, massive material, which under the microscope is seen to be of somewhat doubtful homogeneity. It is intermixed with areas of franklinite that it is apparently replacing.

Occurrence
Very few specimens of glaucochroite have been preserved. The mineral came from the same part of the Parker shaft as clinohedrite and like it was found only on the mine dump. The crystals are embedded in nasonite or willemite, from which they are readily separated, but owing to their extreme brittleness they are generally in fragments. They are intimately associated also with garnet and yellow axinite. The terminated crystals described here were embedded in transparent green willemite or were implanted upon it, together with minute crystals of clinohedrite.

Figure 110 Crystal of glaucochroite showing the forms b(010), m(110), s(120), and x(103). Franklin.
	Figure 111 Crystal of glaucochroite showing the a(100), b(010), m(110), s(120), k(021), e(111), and f(121). Franklin.

Crystals described by Gordon (222) as glaucochroite were shown by Schaller (Gordon, 226), by determination of the optical characters, to be tephroite.

The only other discovery of glaucochroite at Franklin was made in 1927, when specimens from the deep levels of the mine were found on the picking table. The glaucochroite here is in coarse granular form of bluish color, intimately mixed with willemite, hardystonite, tephroite, and franklinite. Analysis 3, in the table above, represents this material.

Material known locally as "calcotephroite" was found abundantly at Franklin about 1924 and was analyzed as shown above in no. 2. It is very dense and fine grained, white when first taken from the mine but soon turning dark brown upon exposure to the light. It appears to be a very impure variety of glaucochroite.