Mineralpedia Details for Natrolite

Named for the Greek for “sodium,” natrio, in reference to the mineral’s sodium content, and for “stone,” lithos. Natrolite is a common mineral that occurs in cavities in basalts and other igneous rocks as one of the last minerals to forms, and also occurs as a filling in seams in granites, gneisses, and syenites. Associated minerals include zeolites, calcite, nepheline, sodalite, and quartz. Natrolite hundreds of known localities including in Germany, France, England, Ireland, Norway, Russia, the United States, and Canada. Natrolite is pyroelectric and piezoelectric, and will generate a charge in response to temperature and pressure changes, respectively. It will commonly fluoresce an orange to yellow under ultraviolet light.

Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/natrolite.pdf

Formula

Na₂(Si₃Al₂)O₁₀·2H₂O 

Crystal System

Orthorhombic 

Crystal Habit

Acicular, Prismatic, Nodular 

Cleavage

Perfect, Imperfect, None 

Luster

Vitreous - Silky 

Color

white, colorless, red, yellowish white, reddish white 

Streak

white 

Class

Orthorhombic - Pyramidal 

Fracture

Brittle 

Hardness

5.5-6 

WebMineral

View Natrolite 

Mindat

View Natrolite 

Clear with tints of orange, bladed Natrolite crystals in fan-like sprays.

Colorless prismatic crysals from 3-15mm showing good terminations.

Creamy white prismatic crystals to 8mm in vug. Note the old tag in the prov. tab from the University of Amsterdam.

Excellent for this mine with colorless Natrolite crystals to 1.5cm.

A very nice divergent spray of colorless Natrolite to 4mm. There are two sprays with other zeolites.