This is a spheroidal crystal of Pectolite. It was produced in Millington Quarry, Basking Ridge, New Jersey, America. University of Tsukuba is owning this. — Photo: Miyuki Meinaka · Public domain
Pectolite
Also known as: Larimar is the blue variety of pectolite.
A white-to-gray sodium-calcium inosilicate forming radiating fibers — its blue variety larimar is a gemstone.
Intro adapted from Wikipedia (CC BY-SA).
Pectolite is an IMA-recognized mineral species in the silicate class, with the chemical formula NaCa₂Si₃O₈(OH).
It crystallizes in the triclinic crystal system (space group P-1). It is a member of the Pectolite structural group.
Key properties: Mohs hardness 4.5–5; specific gravity 2.84–2.9; typically white or colorless or gray; white streak; Silky, subvitreous luster; refractive index 1.616; optically biaxial.
IMA symbol Pct, grandfathered status — known before the IMA’s founding, named in 1828.
Found as a primary mineral in nepheline syenites. A hydrothermal mineral in cavities in basalts and diabases; in serpentinites and peridotites; from metamorphosed high-calcium rocks.
It is found associated with Zeolites, datolite, prehnite.
Its name comes from the Greek for compact, in allusion to its resistance to pulverization.
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