The Mineralogical Record
The Mineralogical Record - Join us on Facebook!  The Mineralogical Record - Sign up for our newsletter

Dennis Tanjeloff
(1967-    )

Dennis Tanjeloff was born in New York City on December 27, 1967, the son of Edgar Tanjeloff (born in Buenos Aires, Argentina in 1941) and grandson of the legendary Julio Tanjeloff (1916-1988). Julio Tanjeloff emmigrated to the U.S. with his family in 1961 and in 1963 opened the spectacular Astro Gallery of Gems and Minerals in New York City, an operation which attracted mineral collectors, gem collectors, interior decorators, architects and designers. By 1976 Julio had engineered an empire of over 20 Astro Gallery retail outlets in various department stores across the country, and also acquired other retail stores outright.

Dennis Tanjeloff was introduced to the world of gems and minerals at the age of four by his grandfather, and as young boy he traveled with him to over 30 countries around the world buying and selling minerals, gems, fossils and related objects of art for the company. Beginning at the age of 13, Dennis worked summers and on weekends throughout high school and college at the family gallery, learning all aspects of the business and absorbing as much knowledge as he could from the 40 years' worth of experience his family had accumulated in the mineral world. He enrolled at Adelphi University in 1987, but in his second year there Julio Tanjeloff passed away of a sudden heart attack, and Dennis left college to help run the family business with his father.

In 1987 Dennis took his first solo trip to the Torino, Italy mineral show to purchase minerals, followed by the Tucson Gem and Mineral Show in 1988. Since then he has not missed a single Tucson Show, and travels throughout the world on buying trips.

In 1990, Astro Gallery of Gems filed for bankruptcy and moved to new headquarters at 185 Madison Avenue in New York City, where they still bill themselves as "World's Largest Gallery of Gems and Minerals." Dennis and his father also built a retail mineral exibit in the Bloomingdale's headquarters in New York City, which remained in place for three years until Bloomingdale's underwent a change in owership.

Dennis succeeded his father Edgar as President of the company in 1996 and has been running all aspects of the operation since then. In 1998 Dennis launched an Internet sales program through an Ebay portal (as "mtmineral"), and through a direct website, which today sells over 600 specimens every month. That same year Marc Tanjeloff, Dennis's youngest brother (born in 1978), joined Dennis in the family business and has worked his way up to being in charge of retail and purchasing operations for Astro Gallery of Gems.

In 2001 Dennis met Marc P. Weill at Astro Gallery of Gems; over the last seven years Dennis has helped and advised Weill in his acquisitions, and has also served as private curator of Weill's collection.

Dennis is a collector himself, and his knowledge of minerals has helped him build a personal collection of fine worldwide minerals currently numbering over 400 specimens which he keeps on display in his home.

Dennis and his wife Margery married in 1999 and have four children: Chloe, Galena , Nicholas and Matthew.

TRINCHILLO, D. (2008) The Marc P. Weill Collection of Fine Minerals. Special supplement to the Mineralogical Record, 39.
To contribute more information please E-mail us at:

[Citation format for this entry:
WILSON, Wendell E. (2019)
Mineralogical Record
Biographical Archive, at]
Click on thumbnail picture to see larger image.
Number of labels found: 1 | Labels being viewed: 1 to 1

The Mineralogical Record - Dennis Tanjeloff Dennis Tanjeloff
Contents copyright © 2019 The Mineralogical Record, Inc. All rights reserved.  
Graphic design of this website by Wendell E. Wilson. Website programming by