Definition of apophyllite
: a mineral composed of a hydrous silicate of potassium, calcium, and fluorine that is related to the zeolites and is usually found in transparent square prisms or white or grayish masses
Learn More about apophyllite
Britannica.com: Encyclopedia article about apophyllite
Seen and Heard
What made you want to look up apophyllite? Please tell us where you read or heard it (including the quote, if possible).