Nesquehonite

Nesquehonite is a mineral of magnesium carbonate (MgCO
₃). It represents the trihydrate of magnesium carbonate, and has the total formula MgCO₃·3H₂O .^[2] It was described in 1890 by F. A. Genth and S. L. Penfield and is named after its type locality of Nesquehoning, Pennsylvania, where it was sampled from a coal mine.^[2] Nesquehonite can form from the related pentahydrate Lansfordite by dehydration at room temperature.

Nesquehonite
General
Category	Carbonates
Formula	MgCO3·3H2O
IMA symbol	Nes[1]
Strunz classification	5.CA.05
Dana classification	13.1.5.1
Crystal system	Monoclinic
Space group	P21/m
Unit cell	a=7.705 Å, b=5.367 Å, c=12.121 Å, β=90.451°
Identification
Colour	Colourless
Cleavage	Perfect
Mohs scale hardness	2.5
Luster	Vitreous (if fresh)
Diaphaneity	Translucent
Specific gravity	1.824-1.854
Density	1.6
Birefringence	0.114