Herderite Gem Guide and Properties Chart

Herderite is a rare collector’s gem, typically found in smaller sizes. This mineral occurs in green, bluish green, white, colorless, yellowish, or gray. Herderite was first discovered in Germany in 1828, but Brazil is today's dominant source. Collectors treasure herderite for cyclic and “fishtail” twinned crystals. Some specimens exhibit phosphorescence when exposed to X-rays.

General Information

Classification
Optical Properties
Characteristic Physical Properties
Chemistry & Crystallography

Common Name

Herderite

Species

Herderite

Transparency

Transparent - Translucent

Dispersion

Strength: Moderate Fire Value: 0.017

Refractive Index

1.556-1.627

Birefringence

0.023- 0.033

Optic Character

Biaxial

Optic Sign

Negative

Polariscope Reaction

Aggregate (AGG), Doubly Refractive (DR)

Fluorescence

SWUV: Inert to moderate yellowish white, blue or violet
LWUV: Inert to weak yellowish white

Pleochroism

Unobservable

Hardness

5-5.5

Streak

White

Specific Gravity

2.950-3.020

Toughness

Poor

Luster

Vitreous

Stability

Poor

Fracture

Subconchoidal

Cleavage

Poor, indistinct

Chemical Formula

CaBePO₄(F,OH)

Crystal System

Monoclinic

Chemistry Classification

Phosphate

Herderite Colors

Colorless
Green
White
Yellow

Countries of Origin

Myanmar; Argentina; Russian Federation; Viet Nam; Czechia; United States of America; United Kingdom of Great Britain and Northern Ireland; Spain; Austria; Sweden; Pakistan; Unknown; China; Namibia; Finland; Brazil; Italy; Germany

Care

Normal care.