Alteration product of basalt and similar eruptive rocks.
IMA Status:
Valid Species (Pre-IMA) 1801
Locality:
Bodenmais in Bavaria, Germany. Link to MinDat.org Location Data.
Name Origin:
From the Greek harmos - "I combine" and temseis - "I cut" alluding to the fact that the pyramid divides parallel to the plane that passes through the terminal edges.
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Rinaldi R , Pluth J J , Smith J V , Acta Crystallographica, Section B , 30 (1974) p.2426-2433, Zeolites of the phillipsite family. Refinement of the crystal structure of, phillipsite and harmotome
Physical Properties of Harmotome
Cleavage:
{010} Good, {001} Fair
Color:
White, Gray, Yellow, Red, Brown.
Density:
2.44 - 2.5, Average = 2.46
Diaphaneity:
Subtransparent to translucent
Fracture:
Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.
Habit:
Cruciform - Twinned tabular crystals with a cross-like outline.
Habit:
Striated - Parallel lines on crystal surface or cleavage face.
Habit:
Twinning Common - Crystals are usually twinned.
Hardness:
4-5 - Fluorite-Apatite
Luminescence:
Non-fluorescent.
Luster:
Vitreous (Glassy)
Streak:
white
Optical Properties of Harmotome
Gladstone-Dale:
CI meas= 0.043 (Good) - where the CI = (1-KPDmeas/KC) CI calc= -0.006 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.215,KPDmeas= 0.2046,KC= 0.2137 Ncalc = 1.5 - 1.53