# Hyalite

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> Markdown URL: https://mediated.wiki/source/Hyalite.md
> Source: https://en.wikipedia.org/wiki/Hyalite
> Source revision: 1288584680
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

**Hyalite** is a [transparent](/source/Transparency_and_translucency) form of [opal](/source/Opal) with a glassy [lustre](/source/Lustre_(mineralogy)). It may exhibit an internal play of colors if natural [inclusions](/source/Inclusion_(mineral)) are present. It is also called **Muller's glass**, **water opal**, and **jalite**. Müller's glass is named after its discoverer, [Franz-Joseph Müller von Reichenstein](/source/Franz-Joseph_M%C3%BCller_von_Reichenstein).

## Properties

Hyalite has a [hardness](/source/Hardness) of 5.5–6 on the [Mohs scale](/source/Mohs_scale) and a [specific gravity](/source/Specific_gravity) of 1.9–2.1. Lacking a plane of [cleavage](/source/Cleavage_(crystal)), it has a [conchoidal](/source/Conchoidal) [fracture](/source/Fracture_(mineralogy)). The [transparent or translucent](/source/Transparency_and_translucency) [mineraloid](/source/Mineraloid) has a globular structure, a vitreous [luster](/source/Lustre_(mineralogy)), and a white [streak](/source/Streak_(mineralogy)). Hyalite is an [amorphous](/source/Amorphous) form of [silica](/source/Silica) (SiO2) formed as a volcanic sublimate in [volcanic](/source/Volcanic_rock) or [pegmatic rock](/source/Intrusive_rock) and is thereby considered a mineraloid. It contains 3–8% water, either as a [silanol](/source/Silanol) group or in molecular form.

## Uses

Opalescent hyalite is used in jewellery, and well-formed samples are of interest to collectors due to their unusual appearance, mode of formation and relative rarity. It is sometimes mistaken for resin opal or [silica glass](/source/Silica_glass) since they both may appear clear and globular, but it can be identified under ultraviolet light due to its bright green [fluorescence](/source/Fluorescence).

## External links

- [Mindat data](http://www.mindat.org/min-1959.html)
- [Explanation from Fluorescent Mineral Society](https://www.moregems.com/blogs/news/hyalite-opal-the-real-kryponite)

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